The Real Madrid striker was plagued by thigh and knee problems at the tail end of last season and during this summer's disappointing World Cup adventure in Brazil.
The 29-year-old played all 90 minutes of Monday's Liga opener against Cordoba for his club side, even netting in the dying seconds with a sensational long-range strike.
However, Bento has decided against calling upon the Ballon d'Or holder for the Group I clash with Albania on September 7.
"There's a question over his fitness," Bento is quoted as saying by Marca. "Regardless of having played regularly, he can't compete."
Ronaldo admitted after being crowned Uefa's Best Player in Europe for last season in Monte Carlo on Thursday that he had pushed himself to the limit for Madrid last season and not in peak physical condition.
However, while the former Manchester United man will not feature in the meeting with Albania next month, his Madrid colleagues Pepe and Fabio Coentrao have been included in Bento's 24-strong squad.
Goalkeepers: Eduardo (Dinamo Zagreb), Anthony Lopes (Olympique Lyonnais), Rui Patricio (Sporting Lisbon);
Defenders: Andre Almeida (Benfica), Vitorino Antunes (Malaga), Fabio Coentrao (Real Madrid), Ricardo Costa (Al-Sailiya), Neto (Zenit), Pepe (Real Madrid), Joao Pereira (Valencia), Reuben Vezo (Valencia);
Midfielders: William Carvalho (Sporting Lisbon), Andre Gomes (Valencia), Raul Meireles (Fenerbahce), Joao Moutinho (Monaco), Adrien Silva (Sporting Lisbon), Pedro Tiba (Braga), Miguel Veloso (Dinamo Kiev);
Forwards: Bruma (Galatasaray), Eder (Braga), Ricardo Horta (Malaga), Ivan Cavaleiro (Deportivo La Coruna), Nani (Sporting Lisbon), Vieirinha (Wolfsburg).