Real emerged from Zagreb with a 1-0 win in their Champions League opener.
"It's important to have a good start in the Champions League. We are very happy with three points we took, but I'm not so satisfied with the refereeing," declared Ronaldo.
"I hope we never have this referee again. People talk of fair-play, of protecting good players, but I never get any of that. I don't understand a thing. I'm sad because I hear referees saying they will protect skilful players, but while some are untouchable it seems I can be mauled."