The apparent strike on Monday is the latest in a string of assaults on merchant vessels by missiles or explosive air and sea drones in the Gulf and Strait of Hormuz since the United States and Israel attacked Iran on February 28 this year, killing Iran's supreme leader and other top officials.
Iran's response, striking US and Israeli targets in the region as well as civilian targets in Gulf Arab nations and shipping, has disrupted global trade in energy and other commodities, raising fears of rising prices and recession.
Iran has effectively blocked the Strait of Hormuz, a narrow waterway that normally carries about a fifth of global oil and liquefied natural gas supplies.
Brent crude futures were up over 2% at $US115.17 per barrel in early Asian hours after the news of the attack on the Kuwaiti tanker Al-Salmi in Dubai, but retreated a bit after the Wall Street Journal reported that US President Donald Trump was willing to end the war even if the Strait of Hormuz remains closed.
Earlier, he said US would "obliterate" Iran's energy plants and oil wells if Tehran does not open the Strait.
Brent is on course for a 59% surge in March, its largest monthly gain on record due to the war in the Middle East.
Authorities in Dubai confirmed they were responding to a drone attack on a Kuwaiti oil tanker in Dubai waters and that maritime firefighting teams were working to bring the fire under control.
No injuries have been reported, and the safety of all 24 crew members has been secured, they said.
Work was under way to accurately assess damage to the tanker, said KPC, which according to Lloyd's List Intelligence data is the parent company of the vessel's registered owner and commercial operator.
The tanker was loaded with two million barrels of oil from Kuwait and Saudi Arabia, according to data from Lloyd's and TankerTrackers. Lloyd's listed the destination as Qingdao, China.
Iranian officials could not be immediately reached for comment.
Earlier on Monday, a Greek-owned container ship located off the coast of Saudi Arabia's Ras Tanura reported two separate incidents where projectiles hit water near the vessel, maritime security experts said.
A representative from the Liberian-flagged Express Rome reported two unknown projectiles splashing into the water near the container ship approximately 22 nautical miles (40km) northeast of Ras Tanura at 1.52pm (GMT).
The incidents occurred within one hour of each other and the crew was reported safe, British maritime risk-management group Vanguard said.
The Islamic Revolutionary Guard Corps previously claimed to have attacked the Express Rome on March 11, Vanguard said. The operator of Express Rome did not immediately comment.
No group has claimed responsibility for the strike on the oil tanker or the projectiles.
