What makes you think they're in the Gulf?
Subs operate in the Arabian Sea...and it would be EXTRAORDINARILY RARE for any sub to be there that is not in simple transit.
I have read they can lauch Harpoons out of their torpedo tubes. What else have they done to tweak such "birds" to destroy Iran/Russian air defence systems.
Anyway, even if it is psych-ops Iran may have to deploy forces to look for them eating up resources. Kind of an Ali-Rope-Adope when they come in from the air from "other routes" and have their 707 refuelers ready for the ride home....