The North-West outfit's campaign is likely to result in failure to qualify for the Champions League as the Red Devils are currently seventh in the table, 12 points adrift of fourth place.
When asked by MUTV about the cause of United's poor season, Rooney said: "I don't know, but it's not good enough. We can't lose six homes games in a season and we have to put that right, and make this a place which teams fear again.
"It's probably been the story of our season so far that we've got a couple of good results and then one which sets us back a bit. We know we have to respond. It's a bad night for us all but we have to move on."
United remain in this season's Champions League tournament, and will compete in the quarter-finals next month against Bayern Munich, who clinched the Bundesliga title last night with seven games to play.