Holland striker Van Persie experienced a frustrating and injury-hit season at Old Trafford, as thigh problems restricted him to just 28 appearances.
However, the 30-year-old has scored in friendlies against Ecuador and Ghana in recent weeks as he steps up his recovery from a knee problem.
Dutch coach Van Gaal kept a close eye on Van Persie's most recent rehabilitation having been given permission by his predecessor at United to bring the forward to a training base in Holland.
"He is not 100%, but we have two weeks to go," Van Gaal said. "I think he will be 100%.
"He is coming out of injury but we built him already up in our federation, our medical department. It was under the permission of David Moyes, so we could control him. He has worked very hard.
Van Persie is likely to be given another run-out as Holland take on Wales in Amsterdam on Wednesday in their final friendly before flying to Brazil.
The Dutch then begin their World Cup campaign against holders Spain in a repeat of the 2010 final in Salvador on June 13. They face Australia and Chile in their other Group B games.