Israel's war record also has to give Iran pause - Israel does not fuck around. The 6 day war embarrassed a ton of leaders in that part of the world.
It's easy for people in the US to forget the effects of distance like this, because the US approach to this situation would involve parking a carrier group or three (which Israel doesn't have) off Iran's coast in the Persian Gulf, using those to suppress air defenses, and then using those and strategic bombers (which Israel also doesn't have) to strike ground targets.
Or put another way, fear of Israel's military sure hasn't prevented Iran funding Hezbollah, which would generally be considered an act of war in itself given that Hezbollah then uses those funds to fire rockets and artillery into Israel.