Ronaldo came off in the 25th minute of Portugal's 1-0 Euro 2016 final victory over France due to a left knee injury suffered when French midfielder Dimitri Payet crashed into his side during a ninth-minute challenge.
The former Manchester United man has already begun the rehabilitation process, though he is expected to miss all of his club's preseason programme this summer, including the Super Cup in Trondheim on Aug. 9.
Marcelo, however, is hoping the three-time Ballon d'Or winner will make a quicker recovery than expected.
"I spoke with Cristiano and congratulated him, Pepe too," Marcelo told reporters in Montreal on Thursday. "I don't know much about Cristiano's injury, although I hope that he'll be ready for the Super Cup.
"We've won the last Champions League, but now we have to work and our head is on improving to win more titles.
"We are thinking about the Super Cup, the beginning is always a bit hard, but we are focused on the Super Cup."
Alvaro Morata, who left Real Madrid to sign with Juventus two summers ago, is back at the Bernabeu after Real activated a buy-back clause in his contract. Despite a reported imminent second move away from Los Blancos, Marcelo believes the Spain international can help the team this season.
"We know that Morata always has been a great player," the Brazilian said. "Before he was young, now he has more experience and is going to help us a lot.
"I think that the squad is fine, I'm not the one who decides. Those we have are great players and those we don't have are great too.
"The squad that wins always is the best. I have spent several years without winning titles, although we've had quality players. It is difficult to say if it is the best squad or the second best. But each year Madrid tries to win titles."
Marcelo added that he hopes the club keep on fellow defender Nacho.
"I've known Nacho since Castilla, when he came with us, I have a lot of affection for him," Marcelo said.
"Of course, everyone wants more minutes. I want Nacho to stay, the team wants him to stay, he is important to us both in matches and in training.
"Since I joined Real Madrid I was taught to fight for the team. I hope to be here for many years, leaving my skin for the team. Leave? Only if Madrid throw me out. I want to stay in Madrid, I want to continue my life in Madrid."