Thousands of protesters are expected to join demonstrations during his visit, including plans to fly a blimp over parliament portraying Trump as an angry orange baby.
In the Tuesday memo, the U.S. Embassy in London alerted citizens to the "numerous demonstrations" that could "attract large crowds" that may be less than agreeable toward Americans.
"That is why I welcome President Trump's forthcoming meeting with President Putin - open channels of communication between the U.S. and Russian Federation are key to managing the risks of confrontation".
The giant inflatable "Baby Trump" balloon will be flown near the Houses of Parliament ahead of the protest.
May will host a black-tie dinner for Trump at the stately home that will be attended by senior ministers and about 100 business leaders, including the likes of Blackstone group, Blackrock, Diageo, McLaren and Arup.
On the same day, protests against his visit have been planned outside US Ambassador's residence in Regent's Park where President Trump is reported to be staying overnight.
Trump Baby, designed as a statement of protest as Trump visits the United Kingdom this weekend, was brought to life by a crowdfunding campaign, which exceeded its initial £5,000 (S$9,000) target so exponentially that there are now plans to take the balloon around the world, following - and taunting - the U.S. president wherever he goes.
The world catches the Russian Federation 2018 virus
Most respondents, precisely 21 percent, said they favor France, while England came in second place with 18 percent. I felt something odd in my knee and after talking with the doctor on the sideline we decided I should come off.
Workmen construct fences, before the USA presidential visit at the end of the week, around the US ambassador's residence in Regent's Park in London, Britain, July 10, 2018.
Trump is expected to arrive in London Thursday after a North Atlantic Treaty Organisation summit in Belgium.
On knife crime: The president claimed a hospital in the capital had "blood all over the floors" amid a wave of knife crime, adding: "They say it's as bad as a military war zone hospital".
Trump is also expected to travel to Scotland, where he owns two golf courses. Both of those accords were the result of years of painstaking diplomacy by European leaders - and Trump unilaterally trashed them.
The antipathy between Trump and segments of the British public started during the 2016 presidential campaign, when Trump called for a temporary ban on Muslims entering the United States.
But Trump is unlikely to see many of those who have mobilized to protest against his visit.
The US President is going to be accompanied by 1,000 staff for his working visit to Britain.
Khan has criticized Trump repeatedly over the president's political views, saying earlier this year that Trump is "not welcome" in London.