"We are fighting for the manager and trying to get results to turn this around," Rooney told Sky Sports on Thursday.
"You have a lot of people talking about things they believe are happening, when in reality the people writing that stuff don't know anything that is happening."
Van Gaal, whose side face Stoke City away on Saturday, walked out of his pre-match news conference after five minutes on Wednesday after calling on the assembled media to apologise for their treatment of him.
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Rooney joins England teammates Ashley Young and Phil Jones, along with goalkeeper David de Gea, who have spoken positively about the dressing room atmosphere under Van Gaal.
"We regularly have meetings with the players. Myself, and the other senior players in the squad, and with the manager - we are working together and trying to come to the best solution to help us win football matches," he said.
England's leading goalscorer conceded confidence at Old Trafford was low and that he himself was under pressure after a failing to score in his last five league games. United have dropped to fifth in the Premier League, nine points off top spot.
"I know my performances can be better, I know that. I'm working hard to improve that and try and do my best for the team," Rooney said.
"It is not nice, obviously, getting criticised every week, every game. It is tough for the players to deal with.
"We are proud people, we are proud to play for Man United and when it's not going right then it is hard to take."
(Reporting by Nayan Das in Bengaluru; editing by Justin Palmer)
