Pique, who quit the Spain squad after last year's World Cup, was the most high profile player to feature in Catalonia's 2-1 win after several La Liga clubs blocked their players from representing the team, which is not recognised by FIFA or UEFA.
He was given a raucous reception by supporters but gave a firm response when he heard anti-Spain chants, gesturing towards supporters by wagging his finger and urging them to stop.
"I asked for respect above everything, we have to all preach by example, anything that is a lack of respect should not be tolerated," Pique told reporters.
"It's great that people come to support the team but there's no need to show a lack of respect."
Pique used to have a tense relationship with Spain supporters for criticising the Spanish government's response to the political conflict with Catalonia, which led to him being frequently booed at home games.
He also broke down in tears on the day of the banned referendum in Catalonia on Oct. 1 2017, condemning police violence against would be voters.
Tension between the region and the central government has resurfaced recently due to the ongoing trial of Catalan separatist leaders.
(Reporting by Richard Martin; Editing by Christian Radnedge)
