Fabregas was subjected to whistling from some fans during Sunday's 2-1 win over Athletic Bilbao.
That has prompted Pique, who is currently out injured with a cracked hip, to jump to the defence of his club and international colleague.
"It isn't good to have fans whistling you - particularly at home," he said.
"I think it is a mistake to focus on just one player. Blame it on the players, okay, but not just Cesc.
"The season has not been good and I think we are all part of a group that haven't quite got things right."
Barca's only hopes of silverware this season now rest on claiming the Liga title, although Gerardo Martino's men currently trail leaders Atletico Madrid by four points.
Pique has backed his team-mates to respond next season should they miss out on a trophy this term.
"Maybe it hasn't been our best season, but I'm sure we will end up coming back," he said.
"It isn't the first time we've gone through bad times and we have always bounced back.
"It is mostly down to the players - I've missed that feeling that we were all pulling in the same direction."
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