The striker, 27, apologised on Twitter after two posts on Sunday expressing his frustration.
He complained about sitting in the stand at Inverness and insisted playing was more important than money.
Manager Ronny Deila said that Stokes' remarks "showed a lack of respect" to his team-mates.
Deila also revealed prior to the 3-1 win over Inverness Caledonian Thistle that the matter would be dealt with internally.
Capped nine times by the Republic of Ireland, Stokes moved to Celtic from Hibernian in 2010 and has scored 76 goals for the Scottish champions.
The striker, who is out of contract at the end of the season, has started just once during this campaign, making one other appearance as a substitute.
Anthony Stokes has been suspended by Celtic for two weeks following his social media comments about being left out of the team.