Not convinced it will happen. What would prevent Saudi Arabia from retaliating and introducing a special fee on all ships coming from Iran. It's not like intercepting those massive cargo ships in a small sea is of any difficulty for a well funded military.
Isn't it already happening ?
Geography and missiles? Iran have everything to lose and have been put in a position where they literally have to fight for their existence.
Militarily Iran is a giant and Saudi Arabia is a minnow.