Attacking gulf states has a far higher ROI. They don't have much defense there and Iran can use way more weapons. Its far easier to attack there than Israel which is further away. The US is just way to spread out.
And as we know they can't go we are innocent either.
Supressing US airbases and use of civilian airports close to Iran forces them to takeoff much farther out and aerial refuel, which greatly reduce sortie generation and give Iran much large launch window