He mentioned Republican Senator Lindsey Graham, who said in a tweet on Wednesday that Darroch "always understood the strength of President Trump and referred to him as the "Terminator" who is indestructible and will most likely be reelected".
The Metropolitan Police Counter Terrorism Command is investigating the leak of private memos written by Britain's ambassador to the United States that were published in the Mail on Sunday six days ago. "We have a duty to prevent as well as detect crime, and the previous statement was meant to alert to the risk of breaching the OSA", he said.
On Friday, in a clear shot across the bows of newspapers planning to follow up last weekend's revelations in the Mail on Sunday, Scotland Yard cautioned media organisations against running leaked government documents.
The British government had opened its own inquiry into the leaks this week and noted it had involved the police to ascertain whether any documents protected by the Official Secrets Act had been shared. "That is what they are there for", he told a Tory leadership hustings in Wyboston, Bedfordshire.
Current Foreign Secretary Jeremy Hunt said the leaks had: "Damaged UK/US relations and cost a loyal ambassador his job, so the person responsible must be held fully to account".
In a cable sent afterwards, Darroch indicated there were divisions in Trump's team over the decision, and criticized the White House for a lack of long-term strategy.
They warned that journalists who released further details of the former ambassador's communications could be in breach of the Official Secrets Act.
Johnson pointedly refused to back Darroch during the televised debate on Tuesday, leading to accusations from fellow Conservative Party MPs that he had thrown the ambassador "under the bus" in order to bolster his own ties with Trump.
Trump may have been indebted to "dodgy Russians".
In a tweet on Wednesday, the United States president also accused Iran of "secretly" enriching uranium, in violation of the 2015 Iranian nuclear deal that the USA pulled out of a year ago.
The US president's approach to global trade could wreck the system on which it depends.
The London police said on Friday they have launched an investigation into the alleged leaks of the official memos that led to the resignation of the British ambassador to Washington.
The Society of Editors executive director Ian Murray said the threat to the media in the police warning was "not acceptable" in a free society.
"I can not think of a worse example of a heavy-handed approach by the police to attempt to curtail the role of the media as a defence against the powerful and those in authority", he said. "There are rules around that and there are considerable protections for journalists who do reveal things and that, of course, is the right thing to do".