Mbappe suffered a hamstring injury and Cavani tweaked his hip during the same Ligue 1 match on Aug. 25.
PSG said the duo will return to full training at the end of this week.
Neymar is also unavailable due to suspension. The 27-year-old drew a three-match ban for insulting a referee in the aftermath of PSG's loss to Manchester United.
Icardi, who joined Thomas Tuchel's outfit on transfer deadline day, made his debut off the bench during Saturday's narrow win over Strasburg.
He could lead the line against Madrid, who were reportedly interested in signing the Argentine while he was at Inter.