TEHRAN, Iran — With Iran calibrating how to deal with President Donald Trump, its supreme leader, Ayatollah Ali Khamenei, caustically thanked the new U.S. leader on Tuesday for revealing “the true face” of the United States.

“We are thankful to this newcomer,” Khamenei told Iranian air force commanders, according to a report posted on his official website.

Iranian officials had been showing caution since Trump took office last month. Despite expressing anger at his policies and comments, even hard-liners have taken care not to provoke the new U.S. president.

But on Tuesday, it became seemingly apparent to Iran’s leaders that Trump is not easily ignored. After Khamenei spoke out sarcastically about Trump, others expressed worries.

Iran’s foreign minister, Mohammad Javad Zarif, said in an interview with a local newspaper that he expected “difficult times ahead” for Iran, now that Trump was in charge.

Iran’s president, Hassan Rouhani, defended the nuclear agreement between his country and six world powers, including the United States, by saying that the deal was “win-win” for all.

But Trump — who has described the nuclear agreement as “really, really bad” but has not made any moves to alter it— disparaged Iran again on Twitter, this time in a defense against criticism that he is too close to Russia and its leader, President Vladimir Putin. Trump wondered how President Barack Obama could have made a nuclear agreement with Iran, a country Trump described as “#1 in terror.”

Trump seemed to be summarizing comments by his new defense secretary, Jim Mattis, who on Sunday called Iran the “biggest sponsor of state terrorism.”

Many Iranians have expressed astonishment and ridicule at such assertions, pointing to terrorist groups that despise Iran and the West. First al-Qaida, responsible for the Sept. 11, 2001, attacks, and more recently the Islamic State, which has been killing thousands in the Middle East and is responsible for committing and inspiring attacks in Europe and the United States.

“Trump is trying to corner Iran, to make us bow before the U.S. and change our behavior, or face confrontation,” said Nader Karimi Joni, a political activist close to Rouhani’s government.

Trump included Iran on a list of seven predominantly Muslim countries whose citizens have been barred from entering the United States under an executive order that has been blocked, for now, in the U.S. court system. Trump’s national security adviser, Michael T. Flynn, warned Tehran last week that it had been put “on notice” after an Iranian missile test.

Washington imposed new economic sanctions on 25 people and entities after the missile launch, which Flynn said had violated a 2015 United Nations Security Council resolution approved after the United States and other world powers reached an agreement with Iran on its nuclear program. Iran has asserted that its missile tests do not violate that resolution and fall within its rights to self-defense.

In another possible move against Iran, Trump’s advisers are debating an order intended to designate its Islamic Revolutionary Guards Corps as a foreign terrorist organization, according to current and former officials in the United States briefed on the deliberations.

For Khamenei, Trump’s ascent appears to have vindicated many suspicions harbored by the Iranian leader, who has said many times that the United States cannot be trusted.

“He has proven what we have been saying for more than 30 years — we would always speak about the political, economic, moral and social corruption in the U.S. administration — this man revealed it during the election campaign and since then,” Khamenei said, according to a translated text of the speech.

Hamidreza Taraghi, a political analyst close to Iran’s leaders, said Trump’s “threatening and ranting” style reflected a miscalculation of Iran’s power. “He will soon realize Iran will not be intimidated,” Taraghi said.

© 2017 The New York Times Company