United ended last term empty-handed and have had plenty of time to think about that agonising final day.
And Rooney insists they will be ready when they open up their new campaign against his old club Everton on August 20.
He said: "I'm not sure we need any more motivation but to lose that way was difficult for us to take.
"It's a good chance for us now to bounce back from that. 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.
"City have got some great players. Chelsea have spent a lot of money, so it'll be a close-run thing.
"But this is our chance to show everyone we are a good team and we're capable of winning the league this season. That's obviously our aim this season.
"Ending the campaign without a trophy is a rare thing for United. But we felt we were unlucky in the league. We know we let ourselves down in Europe. That's something we've had to think about. I'm sure we'll be a lot better this season.
"Our first aim will be to improve on last year and we can do that. It's a big season for us after last season and we all need to be ready for it."