The Dutchman has hinted that summer arrival Radamel Falcao is likely to be picked ahead of Rooney in that role, despite the England international having scored two goals so far this season.
"Rooney can play in more positions, he's a multi-functional player and I have tried him in a striker's position," FourFourTwo quotes Van Gaal as saying.
"He has played well, but not spectacular. Falcao is a striker and I think he can do it better."
Rooney was handed the captain's armband by Van Gaal in the summer following Nemanja Vidic's departure.