Real Madrid won 2-1 thanks to goals from Jude Bellingham and Kylian Mbappe on Sunday.
Afterwards, former Arsenal manager Wenger said of the clash: "I felt like they lost Íñigo Martínez in defence, who was one of the most experienced players... Today you can see that the defence against a player like Mbappé lacks maturity and experience.
"Barcelona, without Raphinha and (Robert) Lewandowski, lacked maturity in the decisive moments of El Clásico.
"Xabi Alonso balanced his team well today... Overall, I'd say it was a bit like a men-versus-boys game in some respects."
Wenger also reflected on Mbappe's performance.
He continued: "What did Mbappé do? He came into the game thinking, 'I'll just make runs behind the centre-backs and score one day', and he told his midfielders to look at him every time they had the ball.
"Jude Bellingham's pass was exceptional, and Barcelona didn't have those kinds of players today to make the difference... That class, that special class, gives you the win.
"When you're looking for big matches, it's about taking advantage of key moments."