The Swedish striker scored the only goal of the game to continue the Parisians' unbeaten run.
Ancelotti insisted that his side played better in the second half but admitted that Ibrahimovic was the difference.
"I thank Ibrahimovic," Ancelotti said after the game. "He is a fantastic player.
"We lost here last season, so this is an important win for us. This win will increase the character and personality of the team."
The win means that PSG remain top of Ligue 1, three points ahead of Toulouse.