Iran isn’t suicidal. We’ve already called their bluff on the straight of Hormuz. They’re not going to attempt to close it off since, among other reasons, that would adversely affect China and Russia, the only two major countries that resemble anything like Iranian allies on the world stage.
I could definitely see Iran lobbing tons of missiles against Israel in response to airstrikes on nuclear plants, especially if those airstrikes kill a lot of people. The Iranian public would also probably unify around the current regime, and despise America even more, even if America has nothing to do with the airstrikes. (The nuclear program was even more popular with Mousavi’s “green revolution” than with Ahmadinejad.)
The truly horrifying thing is that Netanyahu and company are operating under the delusion that the opposite is true—that Iran is bluffing in their threats of counterattacks and that in the face of an Israeli attack the Iranian populace will want to give up the nuclear program and depose their dictator. Israel is run by the same sort of right-wing neoconservative nutjobs who pre-emptively waged war on Iraq, thought a “shock and awe” campaign would cow the Iraqi resistance, and that the Iraqis would greet american soldiers as liberators.