The talismanic forward has featured for UEFA Champions League winners Real Madrid at the start of the Spanish season and was on the scoresheet as Carlo Ancelotti's men opened their league campaign with a 2-0 victory over Cordoba last Monday.
Ronaldo struggled with thigh and knee issues during Portugal's disappointing World Cup campaign, which saw them fail to progress from the group stages in Brazil.
And head coach Bento believes the 29-year-old is not physically ready for Portugal's 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."
While Ronaldo will not feature, Real will have representation in the 24-man party with Fabio Coentrao and Pepe having both been selected.
Squad in full:
Eduardo (Dinamo Zagreb), Anthony Lopes (Lyon), Rui Patricio (Sporting Lisbon); 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); William Carvalho (Sporting Lisbon), Andre Gomes (Valencia), Raul Meireles (Fenerbahce), Joao Moutinho (Monaco), Adrien Silva (Sporting Lisbon), Pedro Tiba (Braga), Miguel Veloso (Dinamo Kiev); Bruma (Galatasaray), Eder (Braga), Ricardo Horta (Malaga), Ivan Cavaleiro (Deportivo La Coruna), Nani (Sporting Lisbon), Vieirinha (Wolfsburg)