Donald Trump is refusing to visit the UK, unless Prime Minister Theresa May bans protests.
The US President issued his ultimatum to Ms May over the phone: "He would not be coming to the UK, until she could promise him a warm welcome," according to Bloomberg.
During the same conversation, he complained of negative coverage of himself in the UK press, and she replied there was little she could do.
The conversation builds on the tension between the two world leaders, including a fallout over Mr Trump sharing footage from a UK extremist group.
After he was criticised by Ms May, he tweeted to her: "Don't focus on me, focus on the destructive Radical Islamic Terrorism that is taking place within the United Kingdom. We are doing just fine!"
Last February, Mr Trump cancelled a scheduled trip to open a new US embassy building to London, claiming the old building had been sold for "peanuts".
Ms May visited the White House in last January and Mr Trump is expected to return the visit later this year, although no date has been set.
The two leaders met on Thursday at the World Economic Forum in Davos, Switzerland.
At the meeting, Mr Trump said it was a "a false rumour" that the UK-US relationship was strained.
"We're on the same wavelength in, I think, every respect," he said, according to The Guardian.