Pique and Barca was outclassed by LaLiga and UEFA Champions League titleholder Madrid, which cruised to a 2-0 win in the Supercopa de Espana on Thursday and a 5-1 aggregate victory.
The outspoken Spain international has won six LaLiga titles and three UEFA Champions League trophies among others at Camp Nou but he made the agonising admission as Barca struggle without Neymar after his world-record move to Paris Saint-Germain.
"The season is very long and there is room for improvement," Pique said. But in nine years at Barcelona this is the first time that I have felt we are inferior to Madrid.
"It is true that they won the Champions League last year, but we came here and won not long before that."
Pique said: "We are not in the best moment as a team or a club.
"We must remain as close as possible and try to keep paddling forward.
"It is important for us to live with the defeat and accept that Madrid were better."
Barca – led by Ernesto Valverde – have the opportunity to bounce back when they host Real Betis in their LaLiga opener on Monday (AEST).