The Revolutionary Guard did not capture a second tanker - the British-operated, Liberian-flagged ship Mesdar - in the Gulf, Iran's semiofficial Tasnim news agency reported, quoting regional military sources.
Iran's Islamic Revolutionary Guard Corps arrested a UK-flagged tanker, the Stena Impero, on Friday amid an accident involving the vessel and a fishing boat.
The owner of Stena Impero, Stena Bulk, said the vessel was stopped by "unidentified small crafts and a helicopter" during its transit through the Strait of Hormuz.
But the effort to sign up other countries has run into difficulties because of fears that moving more military assets to the area will inflame tensions with Iran even further, Reuters reported Friday. In June, Iran shot down an American drone in the same waterway, and Trump came close to retaliating with airstrikes. In comments on Twitter on Saturday, Iran's Foreign Minister Mohammad Javad Zarif characterized the seizure of Iran's tanker July 4 as "piracy".
The events have raised concerns that the tensions could lead to a military conflict.
Interested in Iran? Add Iran as an interest to stay up to date on the latest Iran news, video, and analysis from ABC News.
The video shows black and white aerial views of warships moving in water, indicating the time, the date and the geographical co-ordinates.
Operator Stena Bulk said on Friday the tanker had been "in full compliance with all navigation and worldwide regulations".
Given the highly fragile and volatile situation in the Gulf, together with the desperate need to bolster the flagging Iran nuclear accord, was it sensible to detain a vessel carrying Iranian oil off Gibraltar?
"We will respond in a way that is considered but robust and we are absolutely clear that if this situation is not resolved quickly there will be serious consequences", he said.
"Our action in the Persian Gulf is to uphold int'l rules", he wrote in a tweet on Saturday, calling on Britain to "cease being an accessory" to United States sanctions against Iran.
The Mesdar's Glasgow-based operator said communication had since been re-established with the ship and the crew were unharmed.
"The drone was immediately destroyed. after ignoring multiple calls to stand down", he added.
It shows masked forces dropping down ropes onto the ship from a helicopter after it was surrounded by high-speed vessels.
Iran was quick to dismiss President Trump's claim, with one senior official even suggesting it may have targeted its own drone by mistake. Iran's Deputy Foreign Minister Abbas Araqchi tweeted on Friday.
The US is trying to freeze all Iranian oil exports to force the country into reopen talks on the nuclear deal signed in 2015, which America pulled out of past year.
The incident is bound to increase tensions in an already volatile situation.
The current tensions between Iran and the West have been escalating since President Donald Trump withdrew the USA previous year from the 2015 nuclear deal with Tehran with world powers and imposed sweeping economic sanctions on Iran, including its oil exports.
British and US officials said that a second ship, the Liberian-flagged MV Medsar, also was seized.
A day later, Iranian boats attempted to impede a British oil tanker in the region, before being warned off by a Royal Navy ship, according to the Ministry of Defence.
London Saturday advised British ships to avoid the Strait of Hormuz for "an interim period" following Iran's seizure of a British-flagged oil tanker.
Trump said he would talk to Britain about Friday's seizure, which drove oil prices up above $62 a barrel.
The Iranian government has repeatedly denied the accusations.