Brent crude rose 1.1% to $78.88 a barrel on Thursday, while Asian shares mostly slipped after the U.S. launched more airstrikes on Iran and Tehran fired at Bahrain, Kuwait and Qatar.
Trump's declaration a day earlier that the temporary ceasefire was "over" deepened supply fears, with ING saying tanker crossings through the Strait of Hormuz have fallen in recent days.
Hong Kong's Hang Seng fell 0.8%, Shanghai lost 0.5% and Australia's ASX 200 dropped 0.5%, though Japan's Nikkei rebounded 1.6% and South Korea's Kospi edged up 0.1% after Wednesday's 5.4% slide.
Wall Street had already turned lower on the renewed conflict, with the S&P 500 down 0.3% and the Dow off 1.1%, while China's June producer inflation accelerated to 4.1%, adding to concerns that the war is lifting costs more broadly.