Dozens of countries are seeking ways to restart vital energy shipments through the Strait of Hormuz after US President Donald Trump said securing the waterway was for others to resolve.
UK foreign minister Yvette Cooper said Iran's "recklessness" in blockading the Strait was "hitting our global economic security" as she chaired the virtual meeting, which included Australia, France, Germany, Canada, the United Arab Emirates and India.
"We have seen Iran hijack an international shipping route to hold the global economy hostage," Cooper said in opening remarks broadcast to the media before the rest of the meeting took place behind closed doors.
The United States did not attend the talks, one official said.
The discussions, involving representatives of 40 countries, took place after Trump said on Wednesday evening that the Strait could open "naturally" and it was the responsibility of countries that rely on the waterway to ensure it was open.
Iran has largely shut down the key waterway, which carries about a fifth of the world's total oil consumption, in retaliation for US-Israeli strikes which began in late February.
Reopening it has become a priority for governments around the world as energy prices soar.
European countries initially refused Trump's demand to send their navies to the area because of fears about being dragged into the conflict.
But concerns about the effect of the rising cost of energy on the global economy have prompted them to try to form a coalition to see how they can defend their own interests.
European diplomats said putting the coalition together was at an early stage, with the United Kingdom and France leading.
Officials said the discussions on Thursday would focus on which countries were prepared to participate.
France's armed forces spokesman Guillaume Vernet told a news conference on Thursday that the process would be multi-phased and could not happen until hostilities had calmed or ended.
A key focus of the talks would be how to ensure ship-owners could feel confident enough for vessels to resume travelling through the area and to bring down insurance premiums.
There would also eventually need to be co-ordination with Iran to ensure that there will be security guarantees for ships, Vernet said, something that is unlikely for now.
Talks had also started on what military assets could be provided, he said.
"We will need to assemble a sufficient number of vessels and have co-ordination capabilities in the air, at sea, as well as the ability to share intelligence," he said.
The UK said it would host a meeting of military planners for talks next week.
Trump said on Wednesday evening that other countries that use the Strait of Hormuz should "build up some delayed courage" and "just grab it".
"Just take it, protect it, use it for yourselves," he said.
But France's President Emmanuel Macron speaking in South Korea on Thursday said seizing the Strait militarily was an "unrealistic" option.
"It would take an indefinite amount of time, and it would expose all those who venture through this Strait to coastal risks from the Revolutionary Guards, as well as ballistic missiles," he said.
Iran's armed forces responded to Trump with a warning for the United States and Israel of "more crushing, broader and more destructive" attacks in store.
The war will continue until the "permanent regret and surrender" of Iran's enemies, said Ebrahim Zolfaqari, spokesman for the Iranian military's Khatam al-Anbiya central headquarters, in a statement carried by Iranian media.
Iran was drafting a protocol with Oman to monitor traffic in the Strait of Hormuz, the official IRNA news agency cited Deputy Foreign Minister Kezem Gharibabadi as saying on Thursday.
