Ronaldo netted for Juventus in a 2-0 victory over Bayer Leverkusen on Wednesday as they finished their Group D campaign with five wins and a draw.
The Italian champions will be joined in the knockout stages by Group A runners-up Madrid, with whom Ronaldo spent nine memorable years before heading to Turin in 2018.
Madrid are one of five sides Juve could face in the last 16, along with Chelsea, Borussia Dortmund, Lyon and Tottenham, but Ronaldo is hoping to avoid the LaLiga giants for now.
"Real are an extraordinary team, but if you ask me, I'd rather face them later," Ronaldo, who won the Champions League four times with Madrid, told Sky Sport Italia.
"In the final? I would sign up now to meet them in the final."
Ronaldo has scored in three successive matches for Juventus and feels fully over a niggling injury that curtailed his playing time last month.
"I feel good, the physical problems I had have passed," he said. "It was four weeks that I was playing with a little pain, but now I'm fine.
"The team is doing well. We played very well in the second half [against Leverkusen] and are first in the group. Things have improved for me too. I have more confidence and hope to continue like this."
Maurizio Sarri claimed last week that it is not possible to use Ronaldo, Paulo Dybala and Gonzalo Higuain in a front three, with the Juventus head coach instead preferring to rotate.
Ronaldo admitted he likes playing alongside the Argentinian duo but is happy to follow Sarri's plan.
"Whether I play with Dybala or Higuain, it is great," he said.
"I like playing with both of them, we have a lot of fun on the pitch, but the coach is the one who makes the decisions and we must respect them.
"But I can't deny that we have a lot of fun."