Ronaldo was withdrawn after a clash left him with a cut to his face.
He has since received criticism for checking himself with the physio's phone as some suggested a player's looks are unimportant on the pitch, but Zidane insists he was simply trying to see how deep the cut was.
"It's happened now," Zidane said. "He just wanted to know how deep his cut was, that's all.
"I'm just telling you what he said in the dressing room, I'm not going to invent anything. I'm not here to do that.
"It is sewn up and he is training. If he's training with a black eye, that shows the most important thing [for Ronaldo] is to be on the pitch."