The spokesman of the Foreign Ministry said, "We ask the British government to release the Iranian crude oil carrier".
Questioning the legality of the UK's move, Minister Zarif pointed out on Twitter that "Iran is neither a member of the EU nor subject to any European oil embargo".
"These days we witnessed a threatening act from the government of England in the Strait of Gibraltar against a tanker from" Iran, he stated.
Iran has continually denied the vessel was heading to its ally Syria.
A Revolutionary Guard commander had threatened on Friday to seize a British oil tanker in retaliation for the interception of one of Iran's tankers headed to Syria, allegedly in breach of European Union sanctions.More news: Why Queen Elizabeth, Prince Philip Missed Great-Grandson Archie's Christening
More news: Qualcomm to finally release a proper processor upgrade for their smartwatches
More news: Raspberry Pi 4 Won't Work with Some USB Type-C Cables
A day after Iran drew global condemnation for announcing that it was rolling back some of its commitments under its landmark nuclear deal with world powers, the commander of Iran's armed forces said Monday that his country does not want to provoke a conflict.
"Today ... US Ambassador to International Organizations in Vienna Jackie Wolcott requested a special meeting of the Board to discuss the IAEA Director General's latest, concerning report on the Iranian regime's nuclear program", the US mission said in a statement, referring to the IAEA's report on Monday.
The ship was detained 2.5 miles (four kilometers) south of Gibraltar in what it considers British waters, although Spain, which lays claim to the territory, says they are Spanish.
It comes as Iran's foreign minister accused the United Kingdom of "piracy" for seizing and detaining the Grace 1 crude oil supertanker on Thursday.
The IAEA is in charge of verifying the restrictions on Iran's nuclear activities imposed by the deal, which also lifted global sanctions against Tehran.