Iran is roughly four times the population and GDP of Iraq. Beyond the sanctions already in place, what are we going to do to Iran? Invade?
Not that that will stop the US from trying if they ever feel like it. Look at the mess in Iraq, then multiply by 5 or so (Iran + a new civil war in Iraq). You could very well end up with a much worse situation than there is today, loss of hundreds of thousands of lives and a very large chunk of the world with a strong motivation to hate everything and anything the West stands for.
Very Bad Idea.
(I don't have enough information to have an opinion. E.g. something like the bombing of Serbia's infrastructure would be cheap and really bad for Iran, afaik. For a good answer you probably need to ask the military in "relevant" countries.)
And again, for the third time -- this has nothing to do with my point, so you guys can vote this comment down too now, since you obviously just can't give a relevant counter argument. 1/2 :-)