I really think the main reason why the Arabs kingdoms are so against Iran is because of the revolution that happened in Iran. It threaten the Arabs monarchies, and give the clerics the power to control the nation, instead of the royalties controlling the clerics like in the Saudis. The relationship between Iran and its Arab neighbors were fine even close until revolution happened. And so far, I also think it is the Arabs that are showing hostility towards the Iranians, rather than the other way. Iranians are mostly defending themselves