The goalkeeper has been long linked to a move to Real Madrid and the speculation surrounding his future has only intensified as the summer transfer window has worn on.
Van Gaal has already suggested that the De Gea wants to leave Old Trafford, and the coach has now admitted the goalkeeper is not in the right frame of mind heading into the new campaign and will miss his side's Premier League opener against Mauricio Pochettino's men.
"De Gea shall not play, so I don't have any concerns," he told reporters.
"You know that we have problems with De Gea. The Dutch journalists can confirm that I think a human being is more than only a player and he cannot manage that."
While the Dutchman says his side have no injury worries approaching their first league game, he has revealed that new signing Bastian Schweinsteiger and defender Marcos Rojo are not fit enough to feature on Saturday.
"Schweinsteiger also came at the last moment so I don't think he's fit enough. We have to build his fitness.
"It is not possible for Rojo to be match fit either as he was the last player to come back from holiday."
Despite the key absences, Van Gaal feels the Red Devils are in much better shape this year.
"I think that we are far better now than last year when we started, so I have a lot of confidence.
"When we play in the same style and at the same level as the last six months of last season, then we can make a good year."
