Benzema has come under criticism for his perceived lack of effort this season, but Ronaldo has insisted that the Frenchman is "in good spirits".
"Every player has good and bad moments. Benzema is important for the team even though he might not be scoring a lot of goals," Ronaldo told reporters at a press conference.
"He is a professional and he is always ready. I see him in good spirits, he is calm. He always looks to help out the team by scoring or otherwise."
Benzema has been widely linked with a move to the Premier League in January.