US Secretary of State Mike Pompeo said on Thursday that he would go to Iran for talks if it was necessary.
It comes as he contacted his newly appointed British counterpart Dominic Raab for the first time to discuss "key global priorities", including Iran.
Tension between Iran and the US has increased since last year, when President Donald Trump withdrew from the Iranian nuclear deal saying it was not strong enough.
Washington also reimposed sanctions on Tehran.
On Thursday, when asked about Iran, Mr Pompeo said: "Sure. If that's the call, I'd happily go there.
"I would welcome the chance to speak directly to the Iranian people."
The relationship between the two countries has been strained further over the past three months after attacks on oil tankers in the Strait of Hormuz.
Mr Trump and Iranian leaders have both publicly said talks were possible, although each side had different conditions for negotiations to take place.
But on Wednesday, the top military adviser to Iran's supreme leader Ayatollah Ali Khamenei said Tehran would not negotiate with Washington under any circumstances.
Earlier this month he had described the UK's seizure of Iranian vessel the Grace 1 an act of "piracy".
The US State Department spokeswoman Morgan Ortagus said on Thursday: "Secretary Michael R. Pompeo spoke with UK Foreign Secretary Dominic Raab today to discuss key global priorities, including countering Iran's attempts to expand its nuclear program."
She did not mention whether the conversation touched on increased tensions with Tehran over Iran's detention of a British-flagged tanker on July 19 in the Strait of Hormuz.
The seizure has been seen as a tit-for-tat move after British authorities detained an Iranian tanker off Gibraltar earlier this month on suspicion it was shipping oil to Syria in breach of EU sanctions.
Although Mr Trump has adopted a "maximum pressure" campaign against Iran this year, his administration has made clear the tanker is primarily London's issue.
New British Prime Minister Boris Johnson's approach to handling the crisis will be under close scrutiny. It is unclear whether Johnson, who took office Wednesday, will adopt the same hardline approach to Iran as Mr Trump.
In May 2018, while serving as foreign secretary under former prime minister Theresa May, Mr Johnson went to Washington to try to persuade Mr Trump not to abandon the Iran nuclear deal.
He now hopes to seal a trade deal with the US to compensate for a no-deal Brexit.
Ms Ortagus added that Mr Pompeo and Mr Raab discussed "strengthening the NATO Alliance" during their call, an organisation that President Donald Trump has previously criticised.
"We value our close ties with the United Kingdom as we work together to address the world's security challenges," Mr Pompeo tweeted.
Next week, Mr Pompeo will attend a gathering in Thailand for the Association of Southeast Asian Nations (ASEAN), as well as meetings with officials in Australia and Micronesia.
