The Daily Star reports that the Spanish midfielder is 'disillusioned' with his current situation at Old Trafford and is seeking clarification from the Dutch tactician.
26-year-old Herrera is unhappy with the fact he has started just six times in the Premier League and fears his career has stalled under van Gaal.
A source told Starsport: "Ander is worried about his lack of progress at Manchester United under Louis van Gaal.
"He feels like he's lost his identity as a player and doesn't know what his role is anymore.
"His situation appears to be getting worse and he's worried his career is going backwards, so there will have to be a chat with the manager."