"Bad deal. Wanted me to cut ribbon-NO!" tweeted.
The British government has blamed the threat of mass protests for US President Donald Trump's decision to cancel a visit to London to open the new US Embassy, and warned that criticism of the White House risked harming US-British relations.
He said: "This just reinforces what a mistake it was for Theresa May to rush and extend an invitation of a state visit in the first place".
The US will leave behind an imposing 1960 stone and concrete embassy in London's upmarket Grosvenor Square - an area known as "Little America" during World War Two, when the square also housed the military headquarters of General Dwight D Eisenhower.
Johnson, a Trump appointee, also said the new embassy was entirely paid for by the sale of other London properties and "did not cost the US taxpayer a cent".
The US President had been expected to visit the new £750m ($1bn) home for American diplomats on the banks of the River Thames as early as next month.
Some British lawmakers questioned whether would be welcome after he re-tweeted videos from a far-right British group and criticized London Mayor Sadiq Khan following a terror attack past year.
In Washington, White House spokeswoman Sarah Huckabee Sanders said Trump's comment was exclusively about an embassy-related visit.
Trump visit 'would have provoked protests'
Mr Johnson told MPs: "I think Her Majesty the Queen is well capable to of taking this American president - or indeed any American president - in her stride, as she has done over six remarkable decades".
One prominent British Trump fan suggested he may have been looking for a good excuse to call off a visit.
Trump is hugely controversial figure in Britain where he recently succeeded in uniting politicians across the political aisle when he retweeted a far-right group's anti-Muslim videos.
David Lammy, a lawmaker for the opposition Labour party, believed Trump was shaken by the prospect of being " met by millions of us out on the streets protesting".
Mr Johnson tweeted at about 11am: "The US is the biggest single investor in the United Kingdom - yet Khan & Corbyn seem determined to put this crucial relationship at risk". He even got in an extra jab at Khan, calling him a "puffed up pompous popinjay".
Some British lawmakers questioned whether Trump would be welcome in London because of previous tweets and criticism of Muslims and his sniping at London Mayor Sadiq Khan in the aftermath of a terror attack in that city past year.
The comment initially seemed to take No 10 by surprise and a spokesman initially dismissed the idea that Khan had damaged relations: "No, the U.S. and the United Kingdom are natural resilient strong partners and allies and we do more together than any two countries in the world".
Ghana: Trump Language on Africa Unacceptable, Racist
My family came from Italy, among a wave of immigrants from a country perhaps referred to in scatological terms at one time. Another major component of the plan is the inclusion of $1.6 billion for structures including a wall for border security.