But Koeman says the incident is already forgotten.
"What I like to see is passion and they need to understand we need to support each other, but finally I saw a reaction because in this case I think we are too nice together," Koeman said.
"You have to ask, you have to talk and maybe sometimes you need to shout. I don't have any problem with that because it's also an emotional part.
"The two boys spoke already to each other and there's no problem. I like this because you need to do everything to win the game and after you can be friends, but not on the pitch."