Trump isn't super popular in the U.K. Last year, thousands of people protested amid reports May was planning an official visit from Trump.
Khan, meanwhile, has attacked Trump over the president's retweets of an anti-Muslim British hate group, Britain First, which also drew condemnation from Britain's Prime Minister Theresa May.
Human rights groups have vowed to protest against the visit in July.
Asked whether Trump was aware of the "Stop Trump" campaign urging protestors to take to the streets in London, Johnson insisted Trump was "very thick-skinned" and "knows what he wants to do".
Days after he shared racist tweets by the deputy leader of far-right group Britain First, he announced his "working visit" would take place in February of this year to attend the opening of the new United States embassy.
Russian lawyer who met with Trump Jr. says she is an informant
Donald Trump Jr . has said the meeting with Veselnitskaya did not result in the damaging information he was hoping for. Chaika, his representatives and his institutions other than those related to my professional functions as a lawyer".
According to Vice News, approximately 40,000 people said on Facebook that they would attend a protest in London against Trump's visit, while 100,000 others indicated they were interested.
The State Department retweeted the post of British top diplomat Boris Johnson that announced the visit, Xinhua reported.
Sir Kim Darroch, Britain's ambassador to the USA, tweeted that he was "delighted" by the announcement.
Trump has clashed publicly with London's mayor, Sadiq Khan, who has said the president's visit would result in mass peaceful protests and that Trump's values were the polar opposite of Londoners'.
Johnson tweeted: "FANTASTIC news that President Donald Trump will at last come to Britain on 13 July". While the exact details of the trip remain under discussion, Trump could theoretically visit the Queen at Windsor Castle, and never see London at all.
"Most politicians don't lay it out the way that he does so he is going to get a lot of criticism for that as people interpret where he is taking everything.But I think in the end people are starting to even now realise that where he is going is a good direction".