Van Persie scored a penalty in Man United’s 3-1 win over Burnley on Wednesday night but it appears he picked up a knock during the game.
Van Gaal would not go into specifics on the injury however and it is unclear how long the striker will be out.
Speaking about the Dutchman, van Gaal said: ”Robin van Persie also has something, so now I have given the players a day off. Only the injured players have visited our centre, but the doctor has not called me yet so I cannot say anything.”
Van Persie’s injury may be a blessing in disguise for United as he was largely poor against Burnley despite his goal.
The 31-year-old has also failed to strike up an effective partnership with Radamel Falcao in the recent games they have played together.
Even with van Persie out the team United should have enough to get past Preston on Monday.