Accoridng to The Sun, the Red Devils mangaer wants to hold talks with Darmian in a bid to ward off interest from Juventus.
The Premier League club fullback has been heavily linked with a move to the Serie A champions.
He is considering leaving Old Trafford in search of regular minutes and to better his chances of making the Italy squad for the 2018 World Cup.
However, the 54-year-old specialist has made it a top priority to convince Darmian to stay as he views him as a useful squad player.
Mourinho is hopeful of coming to a conclusion on this before they jet off for their pre-season tour of America on July 9.