United's style of play under Louis van Gaal has been a hot topic in recent weeks and there were notable outbursts of frustration from certain sections of the Old Trafford crowd on Saturday as the 20-time English champions laboured to a 2-0 victory over struggling Sunderland.
Rooney, United's captain, told reporters: "I think that's normal. The fans here are always brilliant - they want us attacking at every opportunity but you can't do that all the time.
"Sometimes you have to work the opposition to tire them out which, towards the end, is how you win games."
Restored to a more attacking position after a recent stint in central midfield, Rooney netted both of United's goals against Sunderland to round off a week in which Van Gaal had claimed to be missing a striker who scores 20 goals a season.
Asked if Van Gaal's comments served as motivation, Rooney added: "No, not at all. Everyone knows I've played midfield for the majority of the season, but my record shows that I score goals so I'm not worried about that at all.
"I was obviously pleased the manager played me up front and delighted to get the two goals, but the victory was the main thing because after last week it was important that we bounced back.
"I've said before that it's his [Van Gaal's] decision where he sees me playing and I respect wherever he wants to play me."
