Grimsby have begun an investigation after being “appalled” by a racist comment directed at new signing Tyrell Warren.
The Sky Bet League Two club are working with authorities, including a designated football police officer, following the post on Facebook.
Defender Warren, 25, a former Manchester United youth player, joined the Mariners on Tuesday after leaving divisional rivals Barrow.
“Grimsby Town strongly condemns any form of racial abuse and have a zero-tolerance stance,” read a club statement on Wednesday.
“The club have been made aware and are appalled by a comment made on social media last night.
“We take a zero tolerance stance to any forms of abuse and will not hesitate to issue a club ban to anybody found to have used such language.”