A late header from Alex spared the Ligue 1 leaders' blushes after Guingamp had taken the lead through Mali striker Mustapha Yatabare.
The result extends PSG's lead at the top of the table to six points, but second-placed Monaco can cut the gap to three with a win over Marseille on Sunday.
And, while Blanc accepted that the champions produced a below-par performance, he was highly critical of the condition of the playing surface in Brittany.
"It is always difficult to win games. We came here to win even if we had a lot of respect for Guingamp," Blanc said.
"It is disappointing but I am still satisfied that we never gave up and came back to get a deserved point.
"We were not as good today. Why? I don't want to hide behind it but the state of the pitch was deplorable.
"It is the case for both sides but it handicaps the team that plays the most football.
"We knew it would be difficult and we have to get on with it. It maybe won't be the last time either, but we were not exactly helped."
