Bristol City striker Famara Diedhiou was subjected to racial abuse online after missing a penalty in his side's 1-0 defeat by Swansea City on Saturday.
The Senegal international struck the post from the spot in City's 1-0 loss at the Liberty Stadium, a result which ended their chances of reaching the Championship play-offs.
Connor Roberts gave Swansea the lead on the stroke of half time before Diedhiou, 27, failed to level proceedings as his 69th-minute spot kick cannoned off the post.
After the game, the Senegal international posted a screenshot of a message with three banana emojis, which he received from someone on Twitter. Diedhiou commented, "Why??"
"We stand with Famara Diedhiou and anybody who has to suffer racism in any shape or form. There is no excuse or justification for this disgusting behaviour," Bristol said in a post on Twitter.
The incident comes shortly after Crystal Palace's Wilfried Zaha and Sheffield United's David McGoldrick were subjected to similar abuse on social media.
City also tweeted: "We stand with Famara Diedhiou and anybody who has to suffer racism in any shape or form. There is no excuse or justification for this disgusting behaviour."
Avon and Somerset Police have launched an investigation into the matter.
"We're aware of racist social media message directed at a Bristol City FC player and a formal report has been made to us," a statement from Avon and Somerset Police read.
"Our football liaison officer has been in touch with the club to offer support and confirm an investigation will be carried out. They will be speaking to the affected player in due course to take more details and extend this support directly to him.
"We've contacted Twitter to ensure the post is removed and to get further details about the offender. Early indications suggest the message may have originated from an account holder outside of this country.
"Racist messages of any kind are abhorrent and we want to reassure the player and the club that a full and thorough investigation will now take place."
The incident comes shortly after Crystal Palace's Wilfried Zaha and Sheffield United's David McGoldrick were subjected to similar abuse on social media.
