"They committed many fouls and the problem was that they were not punished for repetitive misconduct, which is also a yellow card. Ramos has not made more fouls than another five or six players in the game.
"The fouls are not always repetitively hard, but when a player makes five you have to show the yellow, and it could have stopped this tactic."
The Dutchman also stood by coach Bernd Schuster's complaints about Izquierdo being Catalan.
He added: "For me, it does not matter where the referee is from. What the coach said was in the heat of the moment, after the game and I understand the emotion of the moment.
"It's something that happens in a hot environment, and he is a man who wants to win at Real Madrid, like all those in the team."