Joleon Lescott had headed the Premier League champions into the lead in the first half, but Laurent Koscielny denied the hosts all three points with a late strike.
The Italian boss feels that his men took their eye off the ball and allowed the Gunners back into the game.
“I don’t know if we lost our concentration but it’s strange,” the home coach told Sky Sports after the game.
“Eight, 10 minutes to go to finish the game, we should have had our concentration 100 per cent.
“We had the game under control. [It was] only for the last 10, 15 minutes… I don’t know why we don’t continue to play.
“We were too deep. The problem is we need to close when we have a chance to score,” he concluded.
Sergio Aguero made a return for City in the game, who now take on Aston Villa at home in the Capital One Cup on Tuesday.
By Gareth McKnight