With the presidential campaign plunged into turmoil last week, Donald Trump’s advisers raced to do the seemingly impossible: transform an often hotheaded candidate into a figure of leadership and calm.

Trump released a cautious statement Friday, expressing dismay about the killing of two black men by the police in Louisiana and Minnesota, and the assassination of five police officers by a sniper in Dallas.

But some close associates feared such a guarded approach would be insufficient. Keith Schiller, a longtime Trump bodyguard and a former police officer, sought to craft an alternative response: He reached out to the New York Police Department to suggest that Trump visit a Manhattan precinct to show solidarity.

Police officials swiftly vetoed the idea. William J. Bratton, the police commissioner, explained sternly: “We’re not in the business of providing photo-ops for our candidates.”

The awkward overture to the police department capped a day of halting, and at times plainly uncomfortable, efforts by Trump and his campaign to respond to the public tragedies. A longtime advocate of blunt law-and-order policies, Trump has run for president as a harsh provocateur, indifferent to conventions of civility and racial tolerance.

But his response to last week’s killings had little of the fire-and-brimstone speech that characterized his response to bloodshed earlier in the campaign.

The episode was a kind of experiment in how Trump, under certain circumstances, can be sculpted into something resembling a conventional presidential candidate. Yet it also highlighted just how limited Trump has proved in the general election — a figure so volatile and hard-line that simply speaking in public can be a risk.

After the attack in Dallas, Trump and his advisers were determined not to repeat the mistakes of his reaction to last month’s massacre in Orlando, Fla., which his aides now see as a political fiasco. After the shooting at a gay nightclub, Trump proceeded with a planned campaign speech in New Hampshire, turning his presentation there into a tirade against American Muslims.

Not so this time: Shortly after gunfire rang out Thursday evening in Dallas, Trump’s campaign chairman, Paul Manafort, argued forcefully in favor of canceling Trump’s events Friday, including a speech in Florida aimed at improving his poor popularity with Hispanics.

When campaign aides convened on a morning conference call, Trump readily agreed to scrap his schedule, according to several people briefed on the campaign’s internal discussions but who were not authorized to speak publicly about them. Manafort said Trump felt it was “not appropriate to campaign” under the circumstances.

An improvisational scramble ensued. Trump advisers had hoped earlier in the week to address the killings in Louisiana and Minnesota with a statement from black leaders who support Trump. By Friday, when the situation had escalated, several senior aides began drafting a more sweeping statement.

It was a halting process: An early, discarded version made reference to crime as foremost in the country’s list of priorities, according to people involved in the drafting. Instead, the first statement released to the media acknowledged the killings of police officers and two men it referred to erroneously as “motorists.” (Only one man, Philando Castile, was in a car when he was shot by a police officer in Falcon Heights, Minn.)

By midday, Trump’s campaign decided to record a statement on video. Speaking from his office at Trump Tower, Trump finally mentioned Castile and Alton Sterling, the man shot by the police in Baton Rouge, La., by name. For the first time Friday, he returned to the ominous language that has defined his campaign.

“We must stand in solidarity with law enforcement,” Trump said, “which we must remember is the force between civilization and total chaos.”

Trump gave no interviews, and his normally active Twitter account sent only five posts. Four were uncontroversial expressions of grief, and the fifth was a jab at Hillary Clinton for her “email lies.”

Darrell C. Scott, a Cleveland pastor who supports Trump, said the candidate’s statements Friday followed several days of deliberation. Scott, a leader of the National Diversity Coalition for Trump, said Trump’s attorney, Michael D. Cohen, had reached out days earlier to ask that the group weigh in on the police shooting in Baton Rouge, the first of the three episodes.

As the week’s violence intensified, Scott said, the pro-Trump coalition and the campaign reacted to the killings in an overall statement Friday. The pastor said he was untroubled by Trump’s imprecise description of one of the two black men killed by the police.

If Friday’s approach shielded Trump from another Orlando-style mistake, he might still have paid a price for his tendency for fulmination and fury. While he was restrained from delivering another diatribe, Clinton canceled only part of her schedule and went forward with an address Friday to the African Methodist Episcopal convention in Philadelphia.

There, Clinton delivered an argument about repairing relations between the police and black communities and confronting “systemic racism” in American institutions.

Trump, trailing in the polls and facing doubts about his temperament, has not displayed similar confidence after any of the tragedies that have rocked the campaign season. His advisers have tried to seize opportunities for him to project a sense of calm leadership. So far, this has been unsuccessful.

A discussion about visiting Orlando after the nightclub attack quickly fizzled. The proposal to visit with New York police officers never came close. Bratton spoke briefly by phone with Trump and Clinton, but a spokesman for the commissioner said Trump did not revisit the idea of meeting with the police.

Trump has also deepened concerns among his advisers and Republican Party leaders with a series of outbursts. These episodes included a meandering speech by Trump Wednesday in Ohio, and a meeting Thursday with Republican senators that descended into a clash with lawmakers who had not endorsed him.

Still, in his first public outings after last week’s killings, Trump stayed close to the message he outlined Friday. On Monday in Virginia, Trump began a speech about veterans’ issues with a scripted tribute to the police; he called himself a “law-and-order candidate” and again acknowledged the deaths of Castile and Sterling.

During a weekend fundraiser at the Hamptons retreat of Wilbur L. Ross, a billionaire New York investor, Trump largely avoided mention of last week’s killings, and focused on reassuring the business-minded Republicans in attendance that he was a safe choice for president.

Trump stressed that he did not consider himself “anti-trade” or “an isolationist,” according to four people in attendance. He polled the 60 or so attendees about who he should choose as vice president, and assessed some of the suggestions.

Newt Gingrich, the former House speaker, had “issues,” Trump said, but had also impressed him with his recent attacks on Clinton. When an attendee suggested Condoleezza Rice, Trump said they had irreconcilable differences over the Iraq War. In one discussion, he mused that Stanley A. McChrystal, the former commander of forces in Afghanistan, might make a good running mate.

He briefly mentioned the sniper attack in Dallas and described the country as gripped by a dark and divisive mood.

John Jay LaValle, chairman of the Republican Party in Suffolk County, N.Y., said Trump had been “on message and extremely focused” in the Saturday gathering.

“Mr. Trump has decided to deal with it head-on, like he does with all issues,” LaValle said.

“People are starting to see we have very serious threats around the world, and even some social unrest in America that, quite frankly, this administration is not keeping a handle on.”