You have to wonder what the mullahs have to gain by making this claim. They know as well as anyone that Shiites like them are targeted for extermination by the Wahhabis and Salafis (who are in fact murdering Shiites in Pakistan and Iraq every single day), and that Israel has nothing to do with it.
There are people who believe these lies... but alo there are others who find the lies to be convenient cover to do those things they already planned but need to justify. The top Nazis didn't believe the propoganda either.