Cavani struggled in PSG's 3-1 UEFA Champions League home loss to Barcelona on Wednesday as the Ligue 1 giants left themselves with work to do in the quarter-final tie.
But Blanc is confident the Uruguay international, who has scored just eight league goals this season, will respond when his side face Nice on Saturday.
"He had a difficult game. As every forward or attacking player, he is upset when he doesn't score," Blanc said of Cavani's performance against Barca.
"He is trying hard to score as quickly as possible.
"I hope he will have the opportunity to do it against Nice and that he will do it."
Late in the Ligue 1 season, PSG sit two points adrift of leaders Lyon – who have played a game more than Blanc's side.
Blanc said PSG had moved on from their loss to Barca, and he talked up the importance of the trip to the Allianz Riviera.
"We will go to Nice with a lot of ambition to get the three points with all respect due to Nice," he said.
"That's our role to get the players to understand even if this game doesn't come at the best moment, it is as important as the coming ones.
"It is the final sprint and we are not allowed to fail. That's my message to the team, to focus on the championship and for the result, we will see tomorrow evening."
