United's Marcus Rashford, Axel Tuanzebe and Anthony Martial, Chelsea defender Reece James, West Bromwich Albion's Romaine Sawyers and Southampton's Alex Jankewitz are among those to have received racist abuse online in recent weeks.
With United set to host Everton on Saturday and City travelling to Liverpool on Sunday, the four clubs came together with the mayors of Greater Manchester and the Liverpool City Region in a show of solidarity.
"Today Manchester United, Everton, Manchester City and Liverpool have come together to support Hate Crime Awareness Week in Greater Manchester," the clubs said in a joint statement.
The statement added: "We condemn the racist abuse that too many players, officials and supporters continue to encounter, most recently on social media platforms."
The Professional Footballers' Association (PFA) has said that those who send abusive messages should be held accountable by authorities and have their social media accounts banned.
"We stand shoulder to shoulder in saying there is no room for racism, hate or any form of discrimination in our beautiful game. It should not happen and it must stop," the clubs and mayors said in their statement.