Barca lost two games in a row for just the third time in the last four years on Sunday, as Iker Muniain's goal gave Bilbao a famous 1-0 triumph.
They entered that fixture on the back of a 2-1 UEFA Champions League loss to Ajax and have stars Lionel Messi (thigh), Victor Valdes and Dani Alves (both calf) and Jordi Alba (hamstring) out injured.
Pique is confident the Catalan giants will respond quickly to their defeats, though.
"The second defeat was very different to the one in Amsterdam," he said.
"Everyone has an opinion, but at San Mames we only conceded the one attempt on goal, which ended up in the net.
"There was a refereeing decision that hurt us. Everything has been mixed in with Ajax. We are not so bad. The sensations from Bilbao were very good.
"Either we can let ourselves sink further or we pick ourselves up. We are playing better, but we are not yet growing in confidence.
"We did not have the desired reaction in Bilbao and on that we must do better. We have ups and downs, like the game in Amsterdam, which was unacceptable."
Barca have an ideal chance to bounce back on Friday when they travel to third-tier Cartagena in the Copa del Rey, an assignment Pique is looking forward to.
"We must demonstrate that we are not in a depression, that we are ready to start winning again," he added.
"The Copa del Rey match on Friday will be a good opportunity for us to play a good game and regain our confidence."
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