The centre-back defended the official's controversial decision to deny Barcelona a penalty and revealed his satisfaction with a second Clasico victory in the space of a week
The reigning Liga champions won their second Clasico in the space of a week, thanks to goals in either half from Karim Benzema and Sergio Ramos, either side of a Lionel Messi equaliser.
But ugly scenes broke out after the game, with Barca protesting Lasa's decision not to award a spot-kick following Adriano's fall in the box.
"I've seen Barcelona doing unusual things, like surrounding the referee at the end. It's not a polite image," Pepe told reporters after the match. "They've lost twice against us and won't be happy.
"I didn't see Adriano's action but it seems like he is the one looking for contact. The referee was perfect. After all, he could also have sent off Thiago [Alcantara], but he had control.
"We've played a complete match. We are so happy. I always believed in the league. As long as it's possible, we'll fight for it.
"Now it's Champions League time, and we are so confident."
Madrid remain in third place in La Liga, but have cut the gap on the Blaugrana to 13 points.