There are a number of things wrong with all this well aside from the strange spectacle of seeing once-fervent liberal critics of old-style Kissingerian realism suddenly espousing Barack Obama's kinder, gentler version of it.
1. The coup that unseated Mohammad Mossadeq was in 1953 nearly six decades ago. Its details are still controversial: the proportional degree of CIA intervention compared to that of the British, the role of fundamentalist clerics in the opposition, the degree to which Mossadeq himself entertained authoritarian measures, and so on. What Kermit Roosevelt Jr. did or did not do as the CIA officer in charge, what were the actual intentions of the Mossadeq government in the Soviet-American Cold War rivalry all of that is all now in the distant past.
Blaming America for undermining Mossadeq but not blaming it for later undermining the Shah is about as logical as claiming we must hold the current generations of Japanese accountable for Pearl Harbor, or that German actions in World War II permanently warped the American psyche, or that the Chinese Communists' butchering thousands of Americans in Korea must be held against current generations of Chinese. At some point, all nations, big and small, need to get a life and move on. Of course, when one rushes in and blabbers out apologies without context, then one becomes a prisoner of those past actions we are to be sorry about Iran then and so must be sorry ever after.
Iran, remember, has no such reluctance about meddling. It endorsed Bush in the 2004 presidential race to the delight of the Kerry campaign. For six years, it has tried to murder Americans in Iraq and destabilize the Iraqi democracy. It has killed Americans in Lebanon and Saudi Arabia, and done its best to thwart democratic government in Afghanistan, Lebanon, and Iraq. How odd that Iranian theocrats have no worries about violently overthrowing democracy abroad, while we are terrified of supporting democracy by words alone.
Criticizing the Ahmadinejad government for its election fraud and its response to peaceful demonstrations is not synonymous with crudely egging on street demonstrations. Reagan found a way to voice support for the Polish resistance to Soviet thuggery. Kennedy made sure that the Berliners knew that we believed they were right and the Soviet-sponsored East German Communists wrong.