The Danish club had made a formal complaint to European football's governing body over the incident which occurred in the 26th minute of their 2-0 defeat at the Nou Camp on October 20.
Copenhagen's Brazilian striker Cesar Santin had the chance to break clear, with the score 1-0 to Barca at the time, but gave up chasing the ball believing he was offside.
In video replays, it is possible to see reserve goalkeeper Pinto waving his arm to indicate the move has been ruled out, and after he has cleared the ball, grinning towards the bench and pointing at himself.
Santin later accused Pinto of simulating the referee's whistle to put him off.
The Spanish champions said in a statement they would appeal the decision, but are likely to have first-choice keeper Victor Valdes back for their next outing in any case.
Pinto, 34, was making his Champions League debut for Barca after Valdes dropped out of the squad with an illness earlier in the day of the Copenhagen game.
