The Red Devils completed an 18-month deal for Victor Valdes earlier in the month and have been heavily linked with a number of players including Mats Hummels and Aymeric Laporte.
But the former Barcelona and Netherlands coach is now looking to sell players, while he also believes the window helps the richer clubs as they look to improve their squads mid-season.
"I don’t think it’s favourable for the league because it’s a little bit unfair," he told reporters.
"You start a league and then you change your team – the richer clubs can do that and it’s not fair for the others. But that’s the rule and you can take advantage of it.
"I read every day that I or United are interested in other players. We have only given a contract to Victor Valdes. We gave him a chance.
"We are only selling players, not buying them."
Anderson and Adnan Januzaj have both been linked with moves from United before the deadline on February 2 while Van Gaal revealed Darren Fletcher is in talks with West Ham.
