At the Downing Street press conference, the Prime Minister was asked what his message was on behalf of those protesting in London in solidarity with Black Lives Matter .
Mr Johnson said: “We mourn George Floyd and I was appalled and sickened to see what happened to him.
"My message to President Trump, to everybody in the United States, from the UK is that I don’t think that racism – and it’s an opinion I’m sure shared by the overwhelming majority of people around the world – racism and racist violence has no place in our society.”
Mr Floyd, a 46-year-old African American, was filmed gasping and pleading “I can’t breathe” as a white police officer knelt on his neck for almost nine minutes.
Thousands of people have been marching from Hyde Park to Parliament Square as worldwide outrage continues to grow over the death of George Floyd in police custody in Minneapolis last week.
Mr Johnson added: “I do think people have a right to protest to make their feelings known about injustices such as what happened to George Floyd. I would urge people to protest peacefully, and in accordance with the rules on social distancing.
"Everybody's lives matter, black lives matter, but we must fight this virus, as well."
The Prime Minister made the comments just a few hours after the leader of the Labour Party Sir Keir Starmer called on him to speak to President Trump about Mr Floyd’s death.
During a clash at Prime Minister’s Questions Sir Keir said: "I'm surprised the Prime Minister hasn’t said anything about this yet.
"But I do hope that the next time he speaks to President Trump he will convey to him the UK's abhorrence about his response to the events."
Both Labour and the SNP have called on the Government to suspend the export of riot control equipment to US during unrest.