Portugal coach Carlos Queiroz had insisted that he intended to call up the world's most expensive player for the matches on Saturday and Wednesday despite opposition from Real Madrid, his club.
But on Tuesday the Portuguese Football Federation admitted that Ronaldo would not be fit enough.
The player is not in good enough physical condition to train with the squad ahead of the play-offs," read a statement by the federation.
Both Portugal and Real had been locked in a battle over Ronaldo - who cost the Spanish club £80 million from Manchester United last summer - with the club insisting that he was not fit enough to travel.
Real Madrid doctors last week estimated that Ronaldo would be out of action for at least two more weeks as he recovers from an ankle injury.
Ronaldo initially injured his right ankle in Real's 3-0 Champions League victory over Marseille at the end of September and aggravated the problem while playing for Portugal on October 10.
"It's impossible for Ronaldo to play with Portugal," Real coach Manuel Pellegrini said on Friday.
"I feel sorry for the Portugal squad and for the player, but he hasn't trained for a long time now and he is still in pain."
