Milan dropped two points drawing with Catania on Saturday.
"The team must not think about the mistakes made in Catania," Allegri declared to Milan's official website.
"We go to Barcelona to play a game for a place in the semi-finals, so the players will have to think about the Champions League now. The Scudetto can wait for a few days.
"The duel with Juventus will last until the end. In their last three games they have beaten Fiorentina, Inter and Napoli, scoring 10 and not conceding in the process. However, they're still behind us."
The tactician took that train of thought further, suggesting that it is taking attention away from his players.
"They are doing well, but less so than us as we have two points more.
"I think people are under-estimating that Milan are doing great things. We have two more points than we had at this stage last season.
"It would have been better to not have suffered those [refereeing] errors and had five or six points more, but the championship would still be open if that was the case."