In the modern era, the difference between sea mine and drone or torpedo can be a lot fuzzier than you may expect. People think of spikey balls, but some sea mines today can do stuff like use passive sonar to match targets against an internal database before firing a homing torpedo. I doubt Iran has these, but they certainly have the proficiency to think creatively about the problem.

I mean you could have some slack in the cable easily, and have the mine become intert should its cable snap.

You have to be mindful of enemy tampering, but overal I would say the idea's worth investigating.

On an unrelated note, I was also thinking of using fiber optic drones to rapidly set up an unjammable communications network on the battlefield. Surely that would be useful for something?