Portugal's team doctor has told Sky Sports News that Ronaldo is expected to go under the knife at the weekend.
But United claim a decision is still to be reached as to whether Ronaldo requires an operation, and issued a statement on their official website.
It read: "Procedures are in place to seek specialist advice, in order to finalise the treatment plan as soon as possible."
The meeting with United officials is reported to be the first time this summer that Ronaldo has spoken to his club since Real Madrid's pursuit of the 23-year-old became public.
Ronaldo, who represented his country as they reached the quarter-finals at Euro 2008, is believed to have delayed the expected operation because he wanted to go on holiday.
Surgery would see Ronaldo sidelined for pre-season, but United will hope their star player is still at Old Trafford and is fit in time for their first game of the 2008/09 campaign, at home to Newcastle on 16th August.