U.S. President Donald Trump flies into Britain on Thursday for talks with the leader of the United States' closest ally in Europe, and tea with Queen Elizabeth, set against a backdrop of protests and what he described as the country's turmoil over Brexit.
The embassy said these demonstrations were expected to attract large crowds and cause road closures.
The US embassy in London says demonstrations over Trump's three-day visit to the United Kingdom, where he is going to meet British Prime Minister Theresa May and Queen Elizabeth, could turn violent, a CNN report stated.
"I do find it curious the amount of opprobrium and time that protesters dedicate to the freely elected leader of a free country, that they don't direct towards the visit of somebody like the president of China", she said.
Mr Khan defended the blimp baby: "There are two issues; one is the freedom to protest and the right to free speech and the second is our issues on President Trump".
A barrage of nationwide protests will greet US President Donald Trump's four-day trip to Britain from Thursday, with organisers hoping to stage one of the country's biggest demonstrations in decades following a series of diplomatic spats.
Then, on the afternoon of Jul 13, a mass protest called Stop Trump March is set to take place.
"For a United States president who retweets far-right Britain First propaganda, insults Londoners at times of tragedy, and refuses to condemn white supremacist marches at home, this insult is well deserved" said Labour MP David Lammy backing the visual protest.
Mr Trump is believed to be spending the weekend playing golf at his Turnberry resort in South Ayrshire, which he bought in 2014, although there has been no official confirmation of his plans.
The blimp's appearance in central London was approved by the Greater London Authority, and Mayor Sadiq Khan has defended the decision, saying it is not for him to be a censor or to decide what is in good or bad taste.
"It's really kind of irrelevant to what we're trying to do, and it certainly doesn't express the opinion of the British people that I've met", Ambassador Johnson said of the balloon. Trump has angered many in Britain in the last two years with a series of actions and pronouncements and many protests are expected.
The couple will attend a black-tie dinner on Thursday at Blenheim Palace in Oxfordshire.
Britain's lawmakers debate a proposal to ban Trump, a Republican presidential candidate, from Britain.