Nick Vallelonga, one of the writers of the film “Green Book,” apologized Thursday for a 2015 Twitter post in which he agreed with then-candidate Donald Trump’s false claim about Muslims, that “thousands of people were cheering” on rooftops in Jersey City, New Jersey, after the Sept. 11, 2001, terrorist attacks.

“I want to apologize,” Vallelonga said in a statement. “I spent my life trying to bring this story of overcoming differences and finding common ground to the screen, and I am incredibly sorry to everyone associated with ‘Green Book.’ “

He went on: “I especially deeply apologize to the brilliant and kind Mahershala Ali, and all members of the Muslim faith, for the hurt I have caused. I am also sorry to my late father who changed so much from Dr. Shirley’s friendship, and I promise this lesson is not lost on me. ‘Green Book’ is a story about love, acceptance and overcoming barriers, and I will do better.”

Trump initially made the statement at a campaign rally in Birmingham, Alabama, when he said: “I watched when the World Trade Center came tumbling down. And I watched in Jersey City, New Jersey, where thousands and thousands of people were cheering as that building was coming down. Thousands of people were cheering.” He kept defending the claim for several days after, even though officials and fact-checkers repeatedly debunked the assertion.

Vallelonga said in a post on Twitter at the time: “@realDonaldTrump 100% correct. Muslims in Jersey City cheering when towers went down. I saw it, as you did, possibly on local CBS news.”

After the post started recirculating this week, Vallelonga deleted his Twitter account.

“Green Book” has seen its stock rise at the beginning of awards season as a result of an unexpectedly strong showing at the Golden Globes. It won three awards there, including for best screenplay, best motion picture (musical or comedy), and for best supporting actor in a motion picture (which went to Ali). Since opening in November, the movie has taken in $37 million at the box office off a $23 million budget.

But the promotional tour has had its hiccups. Viggo Mortensen, one of the film’s stars, apologized in November for using a racial slur at a panel discussion about the movie. Peter Farrelly, director of “Green Book,” apologized Wednesday after The Cut, a website under New York Magazine’s umbrella, uncovered comments from 1998 in which Farrelly said he used to flash his penis to unsuspecting colleagues as a joke.

The film has become one of the most controversial of the season because of its content as well.

“Green Book” tells the story of a black pianist, Don Shirley (played by Ali), who hires a white bodyguard, Tony Lip (Mortensen), as they traverse the South during the civil rights era. Lip was Vallelonga’s father, who also went on to have an acting career himself. His most famous role was his portrayal of Carmine Lupertazzi on “The Sopranos.”

Shirley’s relatives have disputed the characterization of Shirley in the film, including the part about Shirley being estranged from his family, which they say is not true. His family members also said they weren’t consulted about the story. Shirley’s only living brother, Maurice Shirley, has called the movie a “symphony of lies.”

On Tuesday, Vallelonga defended the film at the National Board of Review gala, saying that the story was based on information that Shirley gave directly to him before his death and that Shirley himself told him not to speak to his family. According to website Shadow and Act, Ali called to personally apologize.

Edwin Shirley III, Shirley’s nephew, told the site: “I got a call from Mahershala Ali, a very, very respectful phone call, from him personally. He called me and my Uncle Maurice in which he apologized profusely if there had been any offense.

“What he said was, ‘If I have offended you, I am so, so terribly sorry,’ ” Edwin Shirley III continued. “‘I did the best I could with the material I had. I was not aware that there were close relatives with whom I could have consulted to add some nuance to the character.’ “