Somali sea gangs have seized vessels and crews across the Gulf of Aden and the Indian Ocean, extracting millions of dollars in ransoms.
Mehr did not say where the information on the latest reported attack came from.
Separately on Tuesday, the Pentagon said American forces had rescued six Iranian mariners who said their ship was taking in water off the coast off Iraq.
The announcement came less than a week after U.S. naval forces rescued 13 Iranian fishermen who were taken hostage by pirates in the Arabian Sea for more than a month.
The rescue operations have taken place at a moment of heightened tension between Washington and Tehran over Iran’s nuclear programme, which the West suspects is aimed at building an atomic bomb. Tehran denies the charge, saying its nuclear activities are only for peaceful purposes.
Tehran and Washington do not have formal diplomatic relations. The U.S. State Department last week said there had been no official communication with Iran about the first rescue, which it described as a “humanitarian gesture”.