Khamenei expressed frustration with what he said was Washington's lack of goodwill in approaching Iran on its nuclear program.
"You (the Americans) point the gun at Iran and say either negotiations or we pull the trigger," he was quoted by state-funded broadcaster Press TV as saying. "You should know that pressure and negotiations don't go together and the (Iranian) nation will not be intimidated by such things."
U.S. Vice President Joe Biden told a security conference in Germany that Washington would talk with Iran provided Tehran was serious about negotiations. Later, however, the U.S. Treasury Department tightened sanctions on Iran in an effort to cut off its oil revenue.
"We, of course, understand their need for negotiations, because the Middle East policy of the Americans has failed, and in order to compensate for this failure, they need to play a trump card," Khamenei said.
Kazakhstan this week agreed to host nuclear negotiations between Iran and the five permanent members of the U.N. Security Council, which includes the United States.
Inspectors with the International Atomic Energy Agency said parts of Iran's nuclear program may have a military dimension, an allegation Iran denies.