Amir Hatami, Iran's defence minister vowed that it will respond to Britain detaining its oil tanker at the coast of Gibraltar.
The tanker's seizure "will not be tolerated by us and will not go without a response," he said, reported the Tasnim news agency.
"This move is against international regulations and a kind of a maritime piracy," he added, speaking at a ceremony at Bandar Abbas port in southern Iran.
The tanker is a 330-metre (1,000-feet) Grace 1, capable of carrying two million barrels of oil. It is under detention since Thursday by police and customs agencies in Gibraltar, a British overseas territory on Spain's southern tip.
Authorities in Gibraltar said they suspected the tanker was carrying crude to Syria in violation of EU sanctions. On July 5, Iranian official Mohsen Rezaei, member of advisory panel to Supreme leader Ayatollah Kahminei, said in a tweet that "If Britain does not release the Iranian oil tanker, it is the authorities' duty to seize a British oil tanker."
Gibraltar's Supreme Court ruled Friday that the tanker can be held for 14 more days.
The vessel's detention came at a sensitive time in Iran-EU ties. On Saturday, Hassan Rouhani had said that Iran is ready to make good on the threat to enrich uranium to weapon-grade levels.
