Uhhh, the funny thing is, no matter who attacks Iran the US would suffer the consequences... BIG TIME.
Iran has said they would shut down oil flow throughout the region, especially through the Strait of Hormuz, if they were attacked. Crude oil would immediately spike in price and who the hell knows what the limit would be. $100/barrel, $150/barrel, depends on how much damage is done and the scale of the attacks. We are talking about 2 million barrels of crude DAILY from this region that might not reach its destination, or it could also be destroyed by the Iranian military.
Such oil prices would send the US economy into free fall mode. You don't want to see that.
Not to mention the probable retaliatory attacks by groups like Hezbollah and Iranian factions ready to strike whenever the first attacks on the motherland occur. If you think that just because we didn't pull the trigger means we're safe you're not thinking through this clearly.