Next step, they are going to try harsh language. If that fails, a diplomatic note.
Or, they could just sink the Revolutionary Guard boats.
I remember a few years ago when a Russian ship was seized by Somali pirates. It was recaptured by ruthless Russian special forces who then loaded up the Somali pirates including their wounded into their boat and then riddled it with gunfire sinking it. Videos were made of the event and circulated worldwide. Needless to say Somali pirates never again molested any Russian ship.
I thought pirating a ship was illegal?