Roberto was jeered as he walked off after being substituted, and Pique said: “The whistles towards Sergi Roberto are hurtful.
“I would like to remind people that he is a midfielder, not a winger. He has made a sacrifice to adapt to that position on the pitch.
“People are free to express themselves but I do not like the whistles, they do not help.
“I know the person, he is a spectacular human being and he wants more than anything for this club to be successful.”
Pique said there were still reasons to be optimistic, adding: “We have people like Ansu (Fati) and (Sergio Aguero) Kun who can improve us.”