"Bad deal. Wanted me to cut ribbon-NO", he said.
Here is an assessment of each of the president's claims.
Mr Trump has also been offered a full-blown state visit to Britain but no date has been set amid jitters over protests.
Trump has since indicated his unwillingness to take the trip amid concerns that he would face mass demonstrations.
London Mayor Sadiq Khan has now responded saying that Trump "got the message" from Londoners, and alluded that Trump's real reason for cancellation is fear of protests - something that has been widely speculated.
Khan, who has led opposition to the prospect of a visit by the United States president, had a row with Mr Trump over the response to the London Bridge terror attack last June.
Around 4 per cent of Britons - 2.5 million people - said they would protest a visit, according to a poll past year.
According to BBC North America editor Jon Sopel, Mr Trump felt the embassy was a legacy of his predecessor, Barack Obama, who was in office when the site in Wandsworth was secured in 2008.
According to the White House, the president chose to cancel his plans because he was angry with the deal the Obama administration made to get the new embassy built, and is instead sending Secretary of State Rex Tillerson in his place. "We looked at all our options, including renovation of our current building on Grosvenor Square". It was then sold in 2009 to a Qatari government investment fund, which plans to turn it into a hotel.
The price hasn't been revealed. Washington had considered upgrading the existing facility, but ultimately decided that tougher physical security standards would be easier to meet by constructing a new building.
The new one is in Nine Elms, a former industrial area on the south side of the River Thames that is being redeveloped as a commercial and residential district.
It's not clear when Trump might visit the United Kingdom instead.
London Underground's Northern Line will also be extended, with two stations providing fast links to the city due to open in 2020.
"We woke up to the news as everyone else did in the country and thought it would be a bit of fun", said spokesperson Claire Treacy.
Previous reports suggest that the construction of the new embassy was completely funded "by the sale of other properties in London". It did not give a more precise figure. He refused to attend the building's opening ceremony.