Iran's Foreign Ministry has lodged a formal complaint with the U.N. secretary-general and the International Maritime Organization (IMO) over the U.S. seizure of the Iranian vessel Touska, condemning the move as an "illegal and barbarous act" and saying it violated international law and the ceasefire agreement.
On Sunday, the United States Navy disabled and boarded an Iranian-flagged cargo ship in the Gulf of Oman after its crew refused repeated orders to halt.
This marks the first known use of force against a vessel during the American naval blockade of Iran.
U.S. President Donald Trump announced the incident in a post on Truth Social, saying U.S. Marines have full custody of the ship.
The vessel, the Touska, is a container ship nearly 900 feet long, roughly comparable in displacement to a naval aircraft carrier.
The ministry also called for the immediate release of the vessel, its sailors, crew and their families after the Iranian-flagged commercial ship was seized by U.S. forces over the weekend in the Gulf of Oman.
In a statement shared by the IRNA news agency, Iran's Foreign Ministry said the Islamic Republic was warning of "the very dangerous consequences of this illegal and criminal act by the United States" and stressed the need for the immediate release of the Iranian ship, its sailors, crew and their families.
The ministry said it "strongly condemns" what it described as "the illegal and brutal action" of the U.S. military against the Iranian commercial ship Touska /j84 on Sunday.
It said the seizure was "accompanied by intimidation of the sailors and crew of the ship and their families."
The statement added: "Without a doubt, the Islamic Republic of Iran will use all its capabilities to defend Iran's national interests and security and to protect the rights and dignity of Iranians. It is obvious that the full responsibility for the further complication of the situation in the region lies with the U.S."
Iran said it had formally taken the matter to the U.N. secretary-general and the IMO, while also calling on several international organizations, including the U.N., for "a firm and serious response."
The Foreign Ministry said the seizure violated both international law and the ceasefire agreement.
U.S. Central Command earlier shared photos on social media showing what it said was the Touska vessel, which it said was seized when it "attempted to violate the U.S. naval blockade."
Over the weekend, Donald Trump said the U.S. had taken "full custody" of the Iranian-flagged ship in the Gulf of Oman after "blowing a hole in the engine room."
The incident comes amid continued uncertainty over whether a second round of peace talks between Washington and Tehran will take place in Pakistan this week.
U.S. Vice President JD Vance is reportedly set to travel to Islamabad as part of an American delegation, while Iran has not yet confirmed its attendance.
A senior Pakistani official told Reuters that the country had "received a positive signal" from Tehran about attending the negotiations.