Rooney insists that United will use the disappointment of finishing last season without a trophy to put things right this time round.
He said: "I'm sure we'll be a lot better this season, our first aim will be to improve on last year and I think we can do that.
"I'm not sure we need any more motivation, but to lose the title that way was difficult for us to take."
Rooney also insisted that defending the title is a demanding challenge that could affect rivals Manchester City during the 2012-13 campaign.
"City being champions, they'll have to face that now obviously. Sometimes it can be more difficult," he added.
"We know how hard you have to work to try and win it back but hopefully, come the end of the season, we'll have it back."
United begin the new season with a trip to Goodison Park to face Everton on Monday.