During his speech on Saturday, Khamenei also said Iran considered President Trump to be a “criminal” and said the US must be “held accountable” for recent unrest.
He also claimed on social media that “America’s goal is to swallow Iran”.
Trump has not yet responded to the supreme leader and the BBC has approached the White House for a comment.
The US state department said on Saturday that it had “heard reports that the Islamic Republic is preparing options to target American bases”.
It said Iran would be met with “a very, very powerful force” if it launched such an attack and warned Tehran not to “play games with President Trump”.
The US president said on Wednesday he had been told “the killing in Iran has stopped”, but added that he had not ruled out military action against the country.
His comments came after the US and UK both reduced the number of personnel at the Al-Udeid air base in Qatar.
Officials told CBS, the BBC’s US partner, that a partial American withdrawal was a “precautionary measure”.