Why should we bomb Iran? The internal movement to bring down their government is intensifying (as it is here in the USA, incidentally). The Iranian government just beat up and arrested a bunch of students. We'll see that more and more. But not if we do the Ayatollahs a favor by uniting the people around the government after an air strike!
The Soviets supported the Vietcong, just as Iran supports Iraqi insurgents. We didn't bomb the USSR in response; furthermore, it didn't take an act of war to bring down the Soviet Union, a far greater oppressor and rival than tiny Iran. Lets keep up the containment, keep up the isolation, and their theocratic government will fall on its own. It took only 40 years to bring down the mighty Soviet Union, without a shot fired from our end. Its already been 30 years since the Iranian revolution. Their government doesn't have long.