"We are confident that there will be huge demonstrations against Trump wherever he visits", said Chris Nineham, of the Stop the War Coalition, which is helping to stage the so-called "carnival of protest".
May will meet at Chequers for a series of bilateral talks.
US Ambassador to Britain Woody Johnson told the media here on Friday there was no deliberate plan to keep Trump out of the capital or away from protests, saying the president was focused on his objectives.
President TrumpDonald John TrumpEx-CIA chief Brennan compares Trump to Bernie Madoff Timeline: The controversies of Scott Pruitt Warren: Trump should have fired Pruitt "28 scandals ago" MORE's schedule for his upcoming trip to the United Kingdom has planned minimal time for the president in the city of London, potentially allowing Trump to avoid large-scale protests planned in the city.
If the U.S president wants to visit a traditional London pub during his visit then he will be assured of a warm welcome in one hostelry.
The visit, the first of its kind since Trump assumed presidency in January previous year, was categorized by the U.S. State Department as a "working visit".
Trump will arrive in Britain on July 12 after attending a North Atlantic Treaty Organisation summit in Belgium.
"Prime ministers frequently make use of Chequers for meetings with foreign leaders", she told the publication.
"We need to see that the relationship isn't damaged after these protests", he said.
The US President also sparked a backlash from author JK Rowling, among others, when he lashed out at Khan immediately after a London terror attack previous year which killed seven people and left 48 injured. As head of state, Her Majesty met with every U.S. President since 1952.
It is expected meeting the Queen will be the last of Trump's official duties before he jets off to Scotland, where he owns two golf properties.
In response to the news, former UKIP leader Nigel Farage tweeted that the balloon protest would be "the biggest insult to a sitting US President ever", apparently forgetting the four Presidents who have been assassinated and the racist birther campaign against President Barack Obama which Trump fuelled.
Asked about the president's thoughts on Brexit, the process of leaving the European Union that is putting British Prime Minister Theresa May's leadership under pressure, Johnson said the United States did not favour any particular form of EU exit.
On Sunday, Mr Trump is expected to move on to Finland ahead of his keenly-awaited summit with Russian President Vladimir Putin in Helsinki on July 16.
Mr Johnson said trade would be high on the agenda for bilateral talks between Mr Trump and Mrs May at Chequers next Friday.
Regarding the "Trump baby" balloon, the spokeswoman said it was up to the GLA to explain why they had approved it.
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