Mr Trump, who has already intervened in the upcoming election, is due to land in London on Monday evening to attend a Nato summit involving all leaders of the 29-member military alliance.
But the event comes amid a fractious general election campaign which has seen Mr Johnson under fire over Brexit and the future prospects of the NHS under a Conservative government.
Labour leader Jeremy Corbyn earlier this week made public a 451-page dossier which he claimed showed the health service would be on the table in future trade talks between a Conservative government and Washington.
Tory chiefs have since reportedly expressed concern the US president could sabotage the party’s campaign by making explosive claims about the NHS during his 48 hours in the capital.
Mr Trump is extraordinarily unpopular in the UK, with two out of every three Britons taking a dim view of the former reality TV star, according to YouGov.
Downing Street said Mr Johnson’s schedule would only be revealed on Monday, but The Sun reported on Friday that the prime minister and Mr Trump would be kept apart as much as possible and would hold no bilateral talks during the two-day summit.
Mr Johnson, whose party has a commanding lead in the polls, said himself on Friday it would be “best” if Mr Trump refrained from commenting on the 12 December election.
"What we don't do traditionally as loving allies and friends, what we don't do traditionally, is get involved in each other's election campaigns," he told LBC radio.
"The best (thing) when you have close friends and allies like the US and the UK is for neither side to get involved in each other's election."
But Mr Trump has already waded into the contest, when he said last month that Mr Corbyn would be "so bad" for Britain and that Mr Johnson should form a pact with Brexit Party leader Nigel Farage.
Mr Corbyn has used Mr Trump's praise of Mr Johnson as one of his focal messages to attack the Conservatives in his campaign, saying they would sell off parts of the NHS to US businesses after Brexit if they win the election.
The president has not shied away from commenting on British politics during previous visits, including criticism of Mr Johnson's predecessor Theresa May's Brexit policy.
Mr Trump is likely to be asked about his attitude to future trade talks and whether the NHS should be included, having previously said everything should be on the table.
However, Mr Johnson said he would walk out of trade negotiations if including the health service was a pre-condition.
"First of all the NHS is not for sale. Under no circumstances will this government or any Conservative government do anything to put the NHS up for negotiation in trade talks or privatising anything like that," he said.
Despite Mr Johnson's promises, doctors, nurses and other NHS staff are set to lead a protest outside Buckingham Palace on Tuesday evening to highlight the potential risks to the health service in a future UK-US trade deal.
The march, which starts at Trafalgar Square, will arrive at the Palace when Mr Trump and other Nato leaders are due to meet the Queen around 6pm.
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