The George Floyd mural in Stevenson Square has now been restored by artist Akse P19.
Cllr Nigel Murphy, Deputy Leader of Manchester City Council, said: "This morning we found that the George Floyd mural in Stevenson Square had been defaced with racist graffiti. It was a shocking act that has no place in our city.
"I'm happy to confirm that the artist who was responsible for the mural has already repaired the damage and restored the mural. A huge thank you for their quick action to put right a wrong that has rightly left many people disturbed that this behaviour exists in our society.
"We will continue to help Greater Manchester Police in their investigation and we are determined to bring the person who committed this crime to justice. I would urge anyone with information to get in touch."
Anyone with information should contact police on 101 quoting 610 of 22/07/20 or the independent charity - Crimestoppers, anonymously, on 0800 555 111.