From an interview with a top Iranian official, Mohammad Jafari, who was almost caught when U.S. forces raided an Iranian office in the Kurdish region of Iraq, in Newsweek:

"Iran can never allow the enemies of Iran to return and take power again. 300,000 of our people were martyred by Saddam. ... If we wanted to basically go against the Americans, we know how to do it."

This in an article about how Iran wants to cooperate with the United States.