Ronald Koeman took part in his first Clasico as a coach, a 3-1 home defeat at Camp Nou by Real Madrid. The Barca boss was angry about the penalty given to Sergio Ramos by referee Juan Martinez Munuera.
"I don't understand the referee's decision, VAR only appears when it has to act against Barcelona," Koeman complained to Barca TV.
The Dutchman added: "Whoever tells me that's a penalty is incomprehensible. I did not like it."
Fede Valverde broke the deadlock, Ansu Fati equalised and then Ramos scored from the spot after Clement Lenglet pulled his shirt.
"I don't understand the VAR, all the decisions are against Barca," added Koeman. "None are in favour and there are many examples, like the penalty on Messi against Sevilla, Getafe's red cards, what happened today. Pulls like that happen all the time in the areas."