Paintsil was in action during last Saturday’s highly-anticipated El Trafico clash between city rivals LA Galaxy and LAFC.
The 26-year-old played the full 90 minutes but was powerless to stop his club from losing 2-1 to their bitter rivals.
Timothy Tillman opened the scoring for LAFC after just four minutes but Julian Aude restored parity for LA Galaxy before the half-hour mark.
Denis Bouanga, however, converted a penalty six minutes later to restore LAFC’s lead, which eventually turned out to be the winner.
In the aftermath of the game, some fans of LAFC took to social media to hurl abuse at Paintsil using racial slurs.
Meanwhile, LA Galaxy have declared their support for Paintsil and condemned the racial abuse, insisting the matter has been reported to Major League Soccer (MLS).
“LA Galaxy forward Joseph Paintsil was the victim of a racist social media incident following Saturday’s match against LAFC,” a statement from the club said.
“The club stands with Joseph and anyone who has faced racial abuse through social platforms or anywhere else. The incident was immediately reported to Major League Soccer.
“We are also working with MLS to ensure Joseph has all the resources and support he needs at this time. There is no place for racism in our community, in our league or anywhere else in society.”
Paintsil joined LA Galaxy from Belgian giants KRC Genk in late February and he has quickly settled in and become a key player.
The Ghanaian winger has been involved in two goals and two assists since joining the American club.