“Capture of the Iranian oil tanker based on fabricated excuses ... will not be unanswered and when necessary Tehran will give appropriate answer,” Bagheri said.
British Royal Marines boarded the ship, Grace 1, off the coast of Gibraltar on Thursday and seized it over accusations it was breaking sanctions by taking oil to Syria.
Iran has demanded the immediate release of the oil tanker, while an Iranian Revolutionary Guards commander threatened on Friday to seize a British ship in retaliation.