Iran's president has said his country will not allow President-elect Donald Trump to "tear up" the country's landmark nuclear deal with world powers.
Hassan Rouhani also warned that Tehran will react to any extension of American sanctions.
The comments came during a speech at the University of Tehran commemorating the killings of Iranian students protesting against a visit by then-US vice-president Richard Nixon in 1953.
Mr Rouhani's remarks highlight the situation he faces after Mr Trump's inauguration in trying to defend the deal struck by his moderate administration.
The timing - during an annual remembrance of the killing of students at the hands of the US-backed Shah Reza Pahlavi's security forces - also shows the internal challenges he faces from hard-liners already suspicious of America's intentions.
"The US is our enemy," Mr Rouhani said. "They want to put pressure on us as much as they can."
Mr Rouhani never mentioned Mr Trump by name in his speech, though he prefaced his remarks with noting that "some man... elected in the US".
"Whatever plans he has, it will be revealed later," Mr Rouhani said. "He may desire to weaken the nuclear deal. He may desire to rip up the deal. Do you suppose we will allow this? Will our nation allow this?"
On the campaign trail, Mr Trump called the multi-nation deal "catastrophic" and vowed to renegotiate it, without explaining how.
Mr Rouhani also warned Iran "will show a reaction" if outgoing president Barack Obama signs a law extending some of America's sanctions authority by 10 years.
The law, first passed by Congress in 1996 and renewed several times since then, allows the US to sanction companies for doing business with Iran.
Mr Rouhani has described extending the sanctions as a violation of the nuclear deal. The White House deemed the bill unnecessary but said it did not violate the international accord.