"Manchester United have the opportunity to win [the Champions League] every season," said the Portugal international, who scored in Wednesday's 4-0 defeat of Dynamo Kiev.
"You work for that but this season there is a better chance than last season.
"We have more options. We have new players, we have great quality and when you have quality you have the opportunity to score goals - which is what the players try to do.
"We have better players and they want to win the Champions League and the Premier League. You have to believe."
The victory saw Wayne Rooney and Carlos Tevez both score - with defender Gerard Pique heading the opener - and their burgeoning partnership up front is one of the key factors behind United's success this season.
Rooney has nine goals in the campaign and the Argentina striker five, but it is their link-up play with each other which has caught the eye.
Ronaldo praised the pair for working hard to establish their partnership.
"The last five or six weeks they have played fantastically," he said.
"They know each other, score goals and do a fantastic job."