The Dutchman has been out of action since picking up an ankle injury during his side’s 2-1 defeat at Swansea last month.
And while Van Gaal is pleased with the progress the player is making during his recovery, he will be out for crucial games against top four chasers Tottenham and Liverpool.
Van Persie is expected to be fit after the international break and so can help finish off United’s season.
“He is still with the medical department and needs to take the step to the technical department,” Van Gaal explained to reporters.
“He is always training but the medical department is also sports science so he is training inside, not outside on the pitch.
“Even when he is on the pitch, he is with the medical department.
“He will then take the step to the technical department and then we have a process when he comes into our selection and trains.”
Van Persie will be sidelined as United host Tottenham’s visit at Old Trafford on Sunday (4pm) as well as missing United’s trip to Liverpool on March 22nd.
By Phil Wellbrook