Spain international De Gea is on the radar of the 2014 Champions League winners Real Madrid, according to The Daily Star.
"The same thing as I have always said,” Van Gaal told BBC Sport. “It is a process for David De Gea.
“He will not leave us easily as we have a great club and he wants to participate. But he is Spanish. And he could go to a great club. It is difficult for him to decide.”
Van Gaal made the comments following United’s 1-1 draw with Arsenal at Old Trafford in the Premier League today.
De Gea started the encounter, but he was replaced by fellow Spaniard Victor Valdes in the 74th minute due to an injury.
The 24-year-old joined United from Spanish outfit Atletico Madrid in the summer of 2011 and is considered as one of the best goalkeepers in the world.
The Spain international struggled in his debut season in the Premier League, but over the past three or so years he has been superb and a key player for the Red Devils.
It will be interesting to see what happens regarding De Gea in the summer transfer window. One suspects that United will not sell him on the cheap, but the player’s decision could be decisive.