The people of Iran are fairly pro western but very nationalistic and would likely turn on us pretty quickly.
As it is I worry that we can't keep up support for a decades long war on terror as it is. I fear that a lot more people in the USA and Europe will have to die before there's a serious effort to crush islamic terrorism once and for all and it will require fighting and occupation forces on the scale of WWII across the islamic world.
I suspect we have to get tough with Iran to get Iraq to settle down.
Probably we'll be fighting the enemy in Europe again (the Balkans, anyway).
One important difference (one of several) is that Iran does not one feared dictator like Iraq had.
The president of Iran does not have statues all over the country and toppling them will not have much effect.
To remove the supreme leaders would mean going after the leaders of Shia religion. Not a very promising task.
One needs remember that until 1953 Iranians were pro-American, pro-democratic and quite secular. It was the aftermath of US removal of Mossadeq that drove them to the mosque.