"We have heard and seen disgusting, dehumanizing racism. Behavior that is undoubtedly a criminal act. It will not be tolerated," the Premier League club wrote, announcing that it would report the incidents to the police.
"Nothing about form or league position can ever excuse or explain racist attacks."
The loss against Brighton means the club remains in the relegation zone of the English top flight.
British police launched an investigation in February after four Premier League players - during the same weekend - were subjected to racism.
