"It's not always easy against a Ligue 2 side that plays good football. It wasn't easy," Garde told reporters after the match.
"I think we saw rather a good game, with two teams who were looking to play. The players are happy, and their relationship with the fans is important.
"They're a young team and need to be supported. The crowd did that. In the last 15 minutes, there was a lot of support. That explains the scenes of joy at the end of the game."
Lyon will now face Ligue 1 title hopefuls Paris Saint-Germain in the final.