The "demonstration alert" issued by the embassy also tells Americans to "exercise caution if unexpectedly in the vicinity of large gatherings that may become violent".
As well as in London, protests are expected to take place in Bristol, Newcastle, Leeds, Cambridge and Cardiff after Trump arrives on Thursday.
He will arrive in the United Kingdom on board Air Force One on Thursday afternoon, straight from the North Atlantic Treaty Organisation summit in Brussels, and will carry out a series of engagements on Friday before heading to Scotland for the weekend.
This will be Trump's first visit to England as president.
Even a "Trump baby" blimp will fly with approval from London's mayor.
Harry Kane Heads List Of Reported Madrid Replacements For Ronaldo
Chelsea winger Eden Hazard hints that it is still his "dream" to play for Real Madrid despite the departure of Zinedine Zidane , but insists that he is content at Chelsea .
With tens of thousands of Brits signed up to take part in the protests of President Trump's policies, the embassy further warned that "several of the events are expected to attract large crowds and there will be road closures in connection with these events".
On Sunday he moves on to Helsinki to meet Russian President Vladimir Putin for long-awaited talks on neutral territory. "He'll be laying unusually low for a USA president visiting Britain, thanks to the throngs of protests expected in central London", says Quartz.
According to Murray, the 20-foot-high image of diapered Trump clutching a phone in his tiny hands is supposed to be seen as, "Not a protest against America or Americans".
Issuing a demonstration alert ahead of the presidential trip, the embassy urged people to keep a low profile as protests span three days.
The organizers also said that their crowdfunding was so successful that not only will the blimp fly for Trump's visit but will also be spotted in other worldwide locales.
Americans were advised to "keep a low profile", "be aware of your surroundings", and "monitor local media" during Trump's visit.