Ronaldo will miss the Super Cup.
The injury happened in Portugal's 1–0 win over France as French midfielder Dimitri Payet collided with Ronaldo in the ninth-minute of the game.
Zidane also did not rule out Ronaldo missing the first La Liga game of the season.
The Super Cup will have Real Madrid play against Europa League champions Sevilla.
Real Madrid is set to play Real Sociedad on Aug. 21 in their league opener.