The Italian admitted that he is concerned by his side's recent results, and has promised fans he will make changes to aid the team's recovery.
The capital club was unable to find a way past the Breton outfit, which had been reduced to nine men shortly after the break, and is now without a win in its last three Ligue 1 games.
"I am very angry," he told reporters after the match. "I don't think we had a good attitude on the pitch. It's very difficult at the moment because we lost two home games and that's not possible for the team we want to be.
"We're in crisis and I don't have any problems with saying that. We have to get out of this period quickly, and if we have the attitude, character and professionalism, we should do.
"To get out of it, we need to change something, and I will change that something. Everyone has to do more. I am here to make a team and, at the moment, we are not a team."
The Parisians were without the suspended Zlatan Ibrahimovic for the clash, but Ancelotti does not feel the Swede's absence contributed to the defeat.
"I don't think so because, without Zlatan, we played very well against Marseille. I do not think that our results have been bad because he didn't play."
PSG will look to get back to winning ways when it travels to Dynamo Kiev in Ukraine on Wednesday in Champions League action.
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