Les Gones were humbled 4-0 at Parc des Princes by the Ligue 1 leaders, thanks to goals from Edinson Cavani and Thiago Silva along with two Zlatan Ibrahimovic penalties, which has left Lyon 10th in the table.
"It's hard to swallow, but it's a fair result," manager Garde told reporters. "We were taught a lesson and it was a real kick in the head. We could have lost by even more.
"We started well; we were conscientious and focused, but after Alexandre Lacazette hit the bar, we eased up a bit and Paris took advantage. We made their job easier but still, we were up against a side with a lot of quality.
"We couldn't keep up the good work we had done in the first 30 minutes and we had no luck on front of goal. Here [at the Parc des Princes] a lot of other side will suffer this season. We're not in the same class as Paris."
Lyon host Toulouse at the Stade Gerland on Thursday.