Nicolas Pepe says he is "deeply sorry" after being shown a red card in Arsenal's 0-0 Premier League draw with Leeds United on Sunday.
The 25-year-old was shown a straight red after 51 minutes at Elland Road for headbutting Whites defender Ezgjan Alioski.
Gunners boss Mikel Arteta described the winger's actions as "unacceptable" and the Ivory Coast international has now taken to social media to apologise for his conduct.
"Yesterday I let my team down at a crucial time of the game and there is no excuse for my behaviour," Pepe wrote on Instagram.
"I am deeply sorry and would like to apologise to the fans, my team-mates, my coach and everyone else at the club.”
Pepe was widely condemned for the incident, though Alioski was also criticised for goading his opponent into reacting before tumbling theatrically to the floor with minimal contact.
Former Manchester United defender Patrice Evra said Alioski "deserves an Oscar" for his reaction in the Sky Sports studio after the game.
However, things took a sour turn when both players received abusive messages of a racist and threatening nature online in the wake of the incident, with the police now set to launch a formal investigation.
Leeds and Arsenal both released statements condemning the “vile” abuse and pledged to work closely with the authorities in order to find the culprits.
Despite having an extra man for the majority of the second half, Leeds failed to take advantage, with both sides having to settle for a point in a goalless draw that keeps them in the bottom half of the Premier League.
The incident caps a difficult start to the season for Pepe, who is in his second season at Emirates Stadium after his £72 million ($95m) move from French club Lille.
Sunday’s clash at Elland Road just his second start in the Premier League. The Ivory Coast international has scored once and created just two chances for his team-mates, although one of those did lead to a goal.
The 25-year-old scored eight goals in 42 appearances in all competitions for the Gunners last season.