US President Donald Trump discussed current tensions with Iran with UK Prime Minister Boris Johnson in a call on Friday.
Iran seized the British-flagged Stena Impero a week ago, prompting strong condemnation from the UK and allies.
On Thursday, US Secretary of State Mike Pompeo said he was willing to go to Iran for talks amid tensions between Tehran and Washington, but also called on Japan, Britain and other nations to join a maritime force to guard oil tankers sailing through the Strait of Hormuz.
Tensions between Iran and the US have ratcheted up since last year, when Trump withdrew the US from the Iranian nuclear deal, formally called the Joint Comprehensive Plan of Action, saying it was not strong enough. Washington also reimposed sanctions on Tehran.
Trump and Iranian leaders have both publicly said talks were possible, but the prospect for dialogue appeared to recede on Wednesday when the top military adviser to Iran’s Supreme Leader Ayatollah Ali Khamenei said Tehran would not negotiate with Washington under any circumstances.
Trump congratulated Johnson on becoming British prime minister, succeeding Theresa May who had failed to win over Parliament on her Brexit plan.
Trump said their two governments were already working on a free trade agreement seen as crucial to help Britain once a Brexit deal takes place.
"They agreed that Brexit offers an unparalleled opportunity to strengthen the economic partnership between the UK and United States," said a British government statement.
It said the leaders “both expressed their commitment to delivering an ambitious free trade agreement and to starting negotiations as soon as possible after the UK leaves the EU.”