The Magpies were taking part in the Schalke Cup, in which Schalke and West Ham United will also play, and were 3-0 down to the Spaniards by half-time.
Newcastle were much improved after the break, although Gabriel Obertan's solitary strike was all they had to show for it.
As such, Pardew expressed his disappointment after the game, blaming himself for fielding a team that was 'too young.'
"I take full responsibility for that first half," he told Quest TV.
"I'm kicking myself because maybe, in that team I picked, there wasn't enough experience and it was too young.
"There will be more experienced players in tomorrow's game [their second group game of the tournament]."
Regarding his side's transfer business, Pardew also hinted that there "may be one more signing. Overall this pre-season, we're getting there."
Facundo Ferreyra is widely expected to sign for the Magpies in the coming days, although Pardew may have meant one more signing after the Argentine's deal is complete.
However, former Newcastle man Rob Lee was unimpressed by the pair, suggesting they need to toughen up ahead of the Premier League campaign.
"Scoring goals will be a problem for Newcastle this season," he said in the Quest TV studio.
"Perez and Cabella look neat and tidy but they need to toughen up for the Premier League. I'm sure in a couple of weeks they'll be stronger but they need to start well."