The Italians managed to sink a major British combatant in an Egyptian harbor during WWII in a contraption significantly less sophisticated than this sub. Can't remember the details though.
Diesel electric subs are extremely quiet and the waters of the Persian gulf are very difficult for sub detecting gear. Iranian subs could pose a threat to shipping there.
We're not talking about Cold War submarine tactics here; there's no need to be that subtle. If they manage to run silent, hammer 'em with active sonar until their fillings fall out and their ears bleed. What are they going to do about it?
The Italians sent in swimmers running what amounted to an over sized torpedo and attached limpet mines to the hulls of 2 or three ships.