"We are resisting an unprovoked aggression by the United States," Zarif told NPR in New York City on Sunday.
"I can assure you that the United States will not be able to bring us to our knees through pressure."
"Abandon the illusion that Iran can be defeated by pressure," said Zarif ahead of this week's United Nations General Assembly.
Iranian President Hassan Rouhani will address the UN on Wednesday, where he is expected to introduce a new peace plan for the Persian Gulf region.
The Trump administration last year pulled out of the 2015 nuclear deal between Tehran and world powers and reimposed sanctions the US had promised to lift.
In July, Iran announced it began enriching uranium above levels set in the nuclear deal.