US President Donald Trump threatened more strikes on Iran's main oil export hub Kharg Island over the weekend and said he wasn't ready to reach a deal to end the war which has shut off the vital Strait of Hormuz and shaken up global energy markets.
Trump said Iran wants to negotiate, but Iranian Foreign Minister Abbas Araqchi on Sunday disputed that claim.
"We have never asked for a ceasefire, and we have never asked even for negotiations," Araqchi told CBS' Face the Nation program.
"We are ready to defend ourselves for as long as it takes."
With crude oil prices hovering around $US100 ($A143) a barrel, Trump administration officials insisted all signs point to a relatively quick end to the conflict.
"This conflict will certainly come to the end in the next few weeks - could be sooner than that ... and we'll see a rebound in supplies and a pushing down of prices after that," US Energy Secretary Chris Wright told ABC's This Week program.
Meanwhile, Araqchi sought to project an image of strength.
"It's not a war of survival. We are stable and strong enough," he said.
"We don't see any reason why we should talk with Americans, because we were talking with them when they decided to attack us, and that was for the second time."
With the war entering its third week, Trump said on Saturday that US strikes had "totally demolished" much of Kharg Island and warned of more, telling NBC News, "We may hit it a few more times just for fun".
The comments marked a sharp escalation from Trump, who had previously said the US was targeting only military sites on Kharg, and dealt a blow to diplomatic efforts to end a war that has spread across the Middle East and killed more than 2000 people, most in Iran and Lebanon.
The World Health Organization said it had released $US2 million ($A2.9 million) in emergency funds to countries in the region, which has experienced large-scale population movements with more than 100,000 people in Iran relocating and up to 700,000 in Lebanon internally displaced.
WHO Director-General Tedros Adhanom Ghebreyesus said on Saturday 14 health workers had been were killed in southern Lebanon within a 24-hour period.
Washington has brushed aside attempts by Middle Eastern allies to open talks, three sources told Reuters, and Iran's Revolutionary Guards said on Sunday they had fired more missiles at Israel and three US bases in the region.
But Israel and Lebanon are expected to hold talks in coming days aimed at securing a ceasefire that would see Iran-backed Hezbollah disarmed, two Israeli officials said.
With global air transport heavily disrupted and no clear end in sight, Iran's ability to choke off traffic through the Strait of Hormuz, the conduit for a fifth of global oil and liquefied natural gas, has emerged as a decisive threat to the global economy.
The passage has been effectively closed for most of the world's shipping since the US and Israel attacked Iran on February 28 at the start of an intensive bombing campaign.
The International Energy Agency said oil from its emergency reserves would begin flowing to global markets soon, with member countries pledging to make available 411.9 million barrels.
Trump on Saturday called on China, France, Japan, South Korea, Britain and other countries impacted by the choking off of oil supplies through the Strait of Hormuz to join efforts to reopen shipping lanes.
France has been seeking to assemble a coalition to secure the strait once the security situation stabilises, while Britain is discussing a range of options with allies to ensure the security of shipping, officials said.
Iran's Revolutionary Guards said it had fired more missile and drone barrages at targets in Israel and at US military bases in the region, where Saudi Arabia said it had intercepted 10 attacks. Iran has not yet used its newest missiles, IRGC spokesperson Ali Mohammad Naini said in comments carried by state media.
"Isn't Trump saying that he has destroyed the Iranian navy? If he dares, let him send his ships to the Persian Gulf region," Naini said.
Israel said its jets hit more targets in western Iran, including headquarters of the Revolutionary Guards and Basij militia forces in the city of Hamadan.
with Reuters
