The Uruguay international has come under scrutiny following a dip in form in recent weeks and he failed to impress once again on Sunday as PSG lost 1-0 at Lyon.
Leading the line in the absence of injured top scorer Zlatan Ibrahimovic, Cavani was presented with a glorious chance to level in the second half but went to ground when trying to round goalkeeper Anthony Lopes when he had the goal at his mercy.
Blanc refused to blame his striker, although he did suggest that the player - who has only recently returned to action following a thigh complaint - may have the World Cup in the back of his mind.
Blanc told Canal Plus: "Cavani had a serious injury and he wants to play in the World Cup. He's afraid of a recurrence. Unconsciously, it's necessary that he relaxes."
The PSG coach added: "I feel we could have played a long time without scoring a goal. That is rare for PSG."
Goalkeeper Salvatore Sirigu echoed his manager's sentiments, and urged his team-mates to make sure they bounce back for the Coupe de la Ligue final, also against Lyon, next Saturday.
"We are disappointed with this defeat," he said. "But there is nothing to say, we must look to bounce back, that's all.
"We made mistakes, it's true, but we also created opportunities. We must be focused and approach the game on Saturday with serenity.
"It was hard before, it always is. We must accept defeat, but keep our heads up."
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