The Red Devils have disappointed in England's top flight this season, picking up just 31 points from their 19 matches, which has left them in seventh spot in the division.
The 20-time English champions are currently 11 points behind third-placed Liverpool with a game in hand, and Ronaldo has said that he will not accept finishing any lower than third.
"I don't accept that our mentality be less than being in the top three in the Premier League," Ronaldo told Sky Sports News. "I think to build up good things, sometimes you have to destroy a few things. So why not - new year, new life and I hope that Manchester (United) can be the level that the fans want. They deserve that.
"We are capable of changing things now. I know the way but I'm not going to mention it here because I don't think it's ethical on my part to say that. What I can say is we can do better - all of us. Manchester (United) belongs to important things, so we have to change that.
"I don't want to be here to be in sixth place, or seventh place, or fifth place. I'm here to try to win, to compete. I think we compete but we are not yet in our best level. But we have a long way to improve and I believe if we change our mind, we can achieve big things."
Man United are only six points behind fourth-placed West Ham United with two games in hand on the Hammers and will be looking to return to winning ways in the league against Aston Villa on Saturday. body check tags ::