Defeat for Ronald Koeman's side came just four months after being humiliated 8-2 by Bayern Munich in last season's Champions League campaign.
Griezmann, 29, believes his team-mates must take responsibility for the defeat and questioned their commitment on the field.
The Frenchman said after the contest: "We didn't turn up.
"In the first half they got the better of us. It was a lack of everything: of desire, of attitude, willingness to run, all of it was bad.
"In the second half, there was already a three-goal advantage and it was easier for us but we had a bad day and a bad game.
"Who else can be blamed if we are the ones who play?
"We have to work on this and want to improve, want to play, and only in this way are we going to move forward.
"We are going to try to put the excuses to the side. The only way is to put everything aside is through work and nothing else.
"We have given a very bad account of ourselves, for the fans."
Barcelona, who appointed Ronald Koeman in the summer after last season's disastrous campaign, are still struggling for form on the field.
They sit ninth in LaLiga after 10 matches having won just four matches.
But they have qualified for the knockout stages of the Champions League after finishing second in Group G behind Juventus on goal difference.