Iran “made a very big mistake” in shooting down a US drone, Trump has said.
Tehran’s Revolutionary Guard claimed the attack, using a surface-to-air missile, had sent “a clear message” to the US that it was “ready for war”.
Mr Trump made the comment after quoting praise he had received on a TV news broadcast.
He tweeted: “Iran made a very big mistake!”
It is the latest in an escalating series of incidents in the Gulf region, a critical artery for global oil supplies, since mid-May including explosive strikes on six oil tankers as Tehran and Washington have slid towards confrontation.
Iran has denied involvement in any of those attacks, but global jitters about a new Middle East conflagration disrupting oil exports have triggered a jump in crude prices. They surged by more than $3 to above $63 a barrel on Thursday.
Saudi Arabia, Washington’s main gulf ally, said Iran had created a grave situation with its “aggressive behaviour” and the kingdom was consulting other Gulf Arab states on next steps.
“When you interfere with international shipping it has an impact on the supply of energy, it has an impact on the price of oil which has an impact on the world economy. It essentially affects almost every person on the globe,” Adel al-Jubeir, Saudi minister of state for foreign affairs, told reporters in London.
Tensions flared with Trump’s withdrawal last year from world powers’ 2015 nuclear accord with Iran and have worsened as Washington imposed fresh sanctions to throttle Tehran’s vital oil trade and Iran retaliated earlier this week with a threat to breach limits on its nuclear activities imposed by the deal.