Mbappe was substituted after pulling his hamstring in a 4-0 Ligue 1 defeat of Toulouse last month.
The France forward has been working hard on his recovery over the international break but is not yet ready to return to training.
In an update posted to PSG's official website on Thursday, the club said the Uruguay striker will make a "progressive return to training this week".
📄 Injury update concerning Edinson Cavani, Kylian Mbappé, Thilo Kehrer and Julian Draxler.https://t.co/TDgVk0xPb8— Paris Saint-Germain (@PSG_English) September 12, 2019
Thilo Kehrer and Julian Draxler are undergoing treatment with both players expected to miss Saturday's home game against Strasbourg as a result.
Mbappe and Cavani are unlikely to be fit to take on Real Madrid, however, with PSG opening their Champions League campaign at home to the Spanish giants on Wednesday.
Neymar is also ruled out of that game due to suspension, so PSG coach Thomas Tuchel could be without all three members of his usual front line for the Group A clash.
Former Stoke City forward Eric Maxim Choupo-Moting, who has scored three goals in two Ligue 1 games, is therefore in line to feature.