If that is too complicated for you, our side will be starting it, not Iran. It won't be up to Iran whether there is a war. Iran is going to barrel straight ahead getting nuclear weapons regardless. The only question is whether anyone will have the balls to stop them.
Despite the fact that they act to the contrary, I don't think Iran is stupid enough to go to war with the U.S. simply because we eliminated their chance to get nuclear weapons... I would expect brinkmanship and a LOT of international heat, but no war...
That means Iran will not start a war because we DESTROYED their weapons program, not because we NEGOTIATED them into surrender. They will do a lot of chest pounding and screaming and calling for action in the UN security council, but they would not start a war with the US...