Prices have been whipsawing on Trump's changing comments on the likely duration of the war, which has prompted Iran to attack vessels in the Strait of Hormuz, the conduit for a fifth of the world's oil.
Trump has previously said the war is "complete", and also promised to guarantee the safety of vessels in the strait. In a Fox News interview aired on Friday, Trump said the US would escort shipping there "if we needed to".
Benchmark Brent crude eased about 0.6 per cent to around $US99.80 ($A142.32), still up almost 40 per cent since the start of the conflict.
After nearly two weeks of war, 2000 people have been killed, most of them in Iran, but many also in Lebanon and a growing number in the Gulf, which has for the first time in decades of Middle East conflicts found itself on the front line.
Several million people have been displaced from their homes. As Israeli warplanes pounded Beirut's suburbs with air strikes, Lebanon's interior minister said authorities were unable to accommodate the hundreds of thousands of people who have sought refuge in the capital.
Israel also dropped leaflets threatening Gaza-scale devastation as it deployed more troops to fight Iran-backed Hezbollah and warned of more attacks on Lebanon's infrastructure.
US forces have also suffered casualties. The US military confirmed that all six crew members aboard a refuelling aircraft that crashed in western Iraq were dead.
Iran fired more missiles and drones at Israel, and Iranian drones were reported flying into Kuwait, Iraq, the United Arab Emirates, Bahrain and Oman.
The Israeli military launched strikes across Tehran. It said its air force had struck more than 200 targets in western and central Iran over the past day, including ballistic missile launchers, air defence systems and weapons production sites.
President Masoud Pezeshkian, Foreign Minister Abbas Araqchi and security chief Ali Larijani all appeared in videos verified by Reuters openly attending the rally in a gesture of defiance, despite an assertion by US Defense Secretary Peter Hegseth that the leadership were "cowering" underground.
"People are not afraid of these attacks. As you can see, people have come out in this rain, under these hardships," judiciary chief Gholamhossein Mohseni-Ejei said at the march.
"We will not back down in any way."
With petrol and diesel prices rising at pumps in the United States and around the world, the US on Thursday issued a 30-day licence for countries to buy Russian oil and petroleum products already at sea - where it is not uncommon for consignments to be sold or change their buyer.
The International Energy Agency said on Thursday the war was creating the biggest oil supply disruption in history.
The war has sparked a critical shortage of cooking gas in India, a country with longstanding ties to Iran. Iran has allowed two Indian-flagged liquefied petroleum gas carriers to sail through the Strait of Hormuz, four sources told Reuters.
The US waiver on Russian oil was welcomed in Moscow but left Kyiv and its allies angry.
"Six members of the G7 expressed a very clear opinion that this was not the right signal," German Chancellor Friedrich Merz told a press conference in Norway.
"We then learned this morning that the American government has apparently decided otherwise."
Ukrainian President Volodymyr Zelenskiy said the move could provide Russia with $US10 billion ($A14 billion), adding: "It certainly does not help peace."
Trump said he thinks Russian President Vladimir Putin may be helping Iran a "little bit" in the interview with Fox News Radio that aired on Friday.
"I think he might be helping him (Iran) a little bit, yeah, I guess. And he probably thinks we're helping Ukraine, right?" Trump said, without specifying the nature of that help.
