The UK is believed to have asked its US ally to initially refrain from making inflammatory public statements about the seizure of the Stena Impero by Iran as they sought a diplomatic solution to the crisis.
Donald Trump was noticeably muted in his immediate response and Mike Pompeo, the US secretary of state, said little in the immediate aftermath.
Jeremy Hunt, the foreign secretary, spoke with his counterpart Mike Pompeo, who was in Argentina, on Friday night. British and US officials continued to speak through the night on Friday. White House officials did not push back on reports that the UK conveyed a message to the US that it wanted to try to de-escalate the situation.
Mr Trump had already spoken to Boris Johnson on Thursday, although it was not clear whether they discussed Iran.
The following day, when asked about the Stena Impero, Mr Trump did not give his usual full-throated response to acts of Iranian aggression, instead saying he had "heard about it" and would "work with the UK"
Mr Pompeo was asked about Iran during an interview in Argentina late on Friday, but aid only: "We’re doing everything we can in the United States to de-escalate with Iran. We want them simply to cease being the world’s largest state sponsor of terror."
The softened tone also came as Mr Trump confirmed he had authorised Rand Paul, the anti-interventionist Republican US senator, to speak to Iranian officials
Mr Paul wants to become Mr Trump's "go-between" with Javad Zarif, the Iranian foreign minister, and asked Mr Trump for permission duding a round of golf a week ago.
Mr Trump confirmed late on on Friday: "Rand is a friend of mine. And Rand asked me if he could involved. The answer is yes. We'll see what happens. Iran is showing their colours. It's going to work out very nicely."
However, there are also suggestions that, in private, Mr Trump has become increasingly frustrated with the Iran situation in recent days.
He is believed to have been displeased at the reluctance of Iran's top leaders to meet with him, especially since he stepped back from a planned military strike last month.
There were indications of that frustration during his muted response on Friday when he said: "This only goes to show what I'm saying about Iran. Trouble. Nothing but trouble."
Meanwhile Lt Gen. Robert Ashley, head of the US Defense Intelligence Agency, said he believes Iran "does not want war," and "the outcome would be very horrific for all". Iran was aiming to drive a wedge between the Us and its European allies, he said
Speaking at the Aspen Security Forum, he added: “What you see is an attempt to break that status quo, to look to divide us with our European powers."
The US is already monitoring its commercial cargo ships in the Strait of Hormuz using military aircraft.
Meanwhile, Russia accused the US of “taking advantage” of rising tensions in the region to deploy hundreds of extra troops to Saudi Arabia. Around 500 are being being sent to the Prince Sultan Air Base, east of Riyadh,
Russian senator Konstantin Kosachev said: "Neither Iran nor the United States, by and large, are interested in a real war. However, the game of nerves and the raising of stakes will continue."
Germany's called the seizure of the British tanker an "unjustifiable intrusion" on shipping which "further exacerbates an already strained situation."
A German foreign ministry spokesman said: "Another regional escalation would be very dangerous, it would also undermine all ongoing efforts to find a way out of the current crisis."
France condemned the seizure and said it "harms the needed de-escalation of tensions."
A US defence official told CNN the US is using armed military aircraft to monitor American commercial cargo ships on their passage through the strait, which can take eight hours.
There were no further details given and it was not clear whether the monitoring was being extended to non-US ships.