The 47-year-old believes his side were punished for their complacency after Anderlecht held them to a 1-1 draw at Parc des Princes on Tuesday
The French champions could have secured their place in the last 16 with a win over the Belgians, but Demy de Zeeuw's goal threatened to condemn the hosts to a shock first Champions League defeat of the season before Zlatan Ibrahimovic's equaliser.
Given PSG's dominant 5-0 thrashing of Anderlecht in the previous round of fixtures, there are many who expected a similar disparity between the sides on Tuesday, and Blanc believes such talk allowed complacency to creep into his side's game.
"I wouldn't say there was a lack of desire or investment. We were too average in all areas," he was quoted as saying by RMC. "We had a lot of technical errors, which hasn't happened for some time. Despite this, we still created a lot of opportunities, so we also showed some clumsiness in front of goal.
"It reminds us that before talking about a win or how many goals we will score, we have to win it on the pitch, and tonight, Paris were too average to win.
"Anderlecht have been rewarded for this match. This is a team who had a lot of courage and were very organised.
"I think it's a good wake-up call. The players put in a lot physically, they are very tired, but it was not enough."