Alex Song has been handed a three-game ban after pleading guilty to a charge of violent conduct.
Referee Peter Walton failed to spot the incident but the Football Association has decided to intervene after reviewing video footage.
"Arsenal's Alex Song will begin a three-match suspension with immediate effect after he accepted a charge of violent conduct," read an FA statement.
"Song was charged following in incident during Arsenal's fixture at Newcastle United on Saturday, August 13."
The Cameroon international will miss the Gunners' Premier League fixtures against Liverpool, Manchester United and Swansea City.