Ronaldo has struggled to find the back of the net in La Liga, netting just twice in 10 games, but the forward has scored eight times in the Champions League.
But Kovacic believes it is only a matter of time before the Portuguese superstar recaptures his best form.
"Me and the rest of my team-mates, we see Cristiano as always in good shape," the Croatia international said.
"He's the best player in the world and he has already scored many goals this season and he will score way more goals for sure.
"At the moment the ball is not willing to go in, but as I said before, this is football and sometimes the ball doesn't want to get in the goal, but there's still time left until the end and he will score way more as usual."
As usual, the battle for the Ballon d'Or is widely expected to be between Lionel Messi and Ronaldo, with the winner to be announced on Thursday.
Ronaldo is expected to join the Barcelona superstar on a record five Ballons d'Or and Kovacic said a win would be deserved after Madrid won La Liga and the Champions League last season.
"I think he should win the Ballon d'Or because his year was amazing. He scored many goals, won everything with the team and he was a key piece of that," he said.
"I'm really happy for him. We all are. But the most important thing for us is to win as a team.
"The Ballon d'Or is important for us and for Cristiano because it's amazing to be able to win a fifth Ballon d'Or but as I said, for us the most important thing is to be a team and win for the team."
Madrid host Borussia Dortmund in the Champions League on Wednesday, having already secured passage through from Group H.