A leading Iranian cleric said that if US President Barack Obama “talks nonsense,” his Iranian counterpart, Hassan Rouhani, should “punch him in the mouth.”

In a Friday sermon delivered in April, substitute Tehran prayer leader Ayatollah Ahmad Khatami urged Iranian negotiators participating in nuclear talks with the P5+1 countries, among which is the United States, to remember that Washington was a “hostile enemy” that cannot be trusted.

“The arrogant pharaohs throughout history have always considered themselves superior to everybody everywhere. The actions of the despotic US administration constitute a clear example of this,” Khatami told a gathering of Shi’ite worshipers in a Tehran mosque, according to a translation posted by the MEMRI media monitoring group this week.

In his sermon, Khatami praised the student organization that carried out the violent 1979 takeover of the US embassy in Tehran, which developed into a 444-day hostage crisis.

The hostage crisis in the embassy, known in Iran as the American “spy den,” was likely brought up amid reports that the US had rejected the visa application of Iran’s new ambassador to the UN, Hamid Aboutalebi, who was found to have connections to the student group that kept US citizens hostage for over a year.

But Khatami did not stop there. He also had some advice for the Iranian negotiators participating in nuclear talks in efforts to ink a long-term deal with world powers.

“When our top negotiators enter the room, they should know that when they face the Americans, they face a hostile enemy that cannot be trusted at all,” Khatami said. “Just as you confront them during the negotiations, you must confront them on the level of political declarations… If the American president talks nonsense, our president should punch him in the mouth.”