Two Japanese and Norweigan oil tankers have been left ablaze after suspected attacks, sparking fears of a broader conflict.
The United States has called for the UN Security Council to confront a "clear threat" posed by Tehran, after Washington said Iran was behind an attack on oil tankers in the Gulf of Oman.
The council met behind closed doors to hear US acting Ambassador Jonathan Cohen present a briefing on Washington's assessment that Iran was responsible for the suspected attack on two tankers in the strategic sea lane.
The attacks, which came a month after a similar incident targeting four tankers off the coast of the United Arab Emirates, "demonstrate the clear threat that Iran poses to international peace and security," Mr Cohen said.
"I've asked the Security Council to remain seized of the matter and I expect that we will have further conversations about it and how to respond in the days ahead.”
Washington's view was not shared by other council members, who noted that there was no clear evidence to link Iran to the attacks, diplomats said.
Kuwait's Ambassador Mansour al-Otaibi said council members condemned the violence and that many of them called for an investigation to determine the facts.
"We would like to know who was behind this incident," he told reporters after the meeting.
The latest incident came amid spiralling tensions between Tehran and Washington, which has pointed the finger at Iran over earlier tanker attacks in May.
UN Secretary-General Antonio Guterres said the facts should be established but warned against stoking conflict in the volatile Gulf.
"If there is something the world cannot afford, it is a major confrontation in the Gulf region," he told an earlier council meeting on UN cooperation with the Arab League.
The Norwegian Maritime Authority said three explosions were reported Thursday on board the Norwegian-owned tanker Front Altair after it was "attacked," along with the Singapore-owned ship Kokuka Courageous.
Iran said its navy had rescued 44 crew members after the two vessels, which were carrying highly flammable material, caught fire.
On May 12, four oil tankers - two Saudi, one Norwegian and one Emirati - were damaged in still unexplained attacks in the Gulf of Oman off the United Arab Emirates.
The UAE last week said initial findings of its investigation pointed to the likelihood that a "state actor" was behind the bombings, but did not specifically blame Iran.
The preliminary findings were presented to the council which may consider a response.
These showed that it was "highly likely" that four Limpet mines, which are magnetically attached to a ship's hull, were used in the attacks, placed by trained divers deployed from fast boats.
Oil price spike
World oil prices surged following reports of the suspected attacks, exacerbating tensions in the crude-rich Middle East, analysts said.
"Tension across the Middle East is high - and the attacks on two tankers have further exacerbated the situation, even though there does not appear to have been any damage to the cargos," John Hall, chairman of British-based consultancy Alfa Energy, said.
London's Brent North Sea oil jumped more than four per cent in morning deals before trimming gains.
In afternoon trading, Brent for August delivery stood at $61.99 USD per barrel, up $2.02 USD, or nearly 3.4 per cent from Wednesday.
New York's West Texas Intermediate was up $1.60 or around 3.1 per cent at $52.74 per barrel.
The Gulf of Oman lies at the other end of the strategic Strait of Hormuz from the Gulf, part of a vital chokepoint through which at least 15 million barrels of crude oil and hundreds of millions of dollars of non-oil imports pass.
On May 12, four oil tankers - two Saudi, one Norwegian and one Emirati - were damaged in still unexplained attacks off the port of Fujairah in the United Arab Emirates.
US national security adviser John Bolton said Iranian naval mines were almost certainly behind those attacks without providing any evidence.
The UAE said initial findings of a five-nation investigation delivered to the UN pointed to the likelihood a state was involved.
King Salman of Saudi Arabia warned this month that "terrorist" attacks in the Gulf could imperil global oil supplies, as he sought to galvanise support against arch-rival Iran.
The kingdom, the world's top oil exporter, ratcheted up tensions with Iran after the attacks off Fujairah, which were followed by a drone strike on a key Saudi oil pipeline claimed by Yemen's Iran-aligned Huthi rebels.
"We are in a dangerous moment in the region with this emerging pattern of attacks," said Elizabeth Dickinson, senior analyst with International Crisis Group.
"Any miscalculation or misunderstanding risks a spiral toward more direct confrontation," she told AFP.