The Brazilian's contract runs out by next June, and the former FIFA World Player of the Year admits that he is yet to be worth of an extension.
"I’m going to try and impress this year to win the trust of the club," the 30-year-old striker told Sky Sport Italia.
"I want to earn things for myself and at the moment I haven’t deserved an extension.
"If I manage to impress then I don’t see there being problems in negotiations with the club at the end of the season, but I need to get stuck in as I don’t want anything gifted to me."
Ronaldo made his season debut for the Milanello in the 2-1 win at Cagliari on Sunday, as he struck the post and managed to win a first-half penalty, missed by Kaka, for Carlo Ancelotti's team.
The former Inter Milan ace, who joined in from Real Madrid last season, was hit with a series of injuries that hindered his progress with the Rossoneri so far.