The Napoli centre-back has been linked with several clubs across Europe, with United thought to be among the interested parties.
But according to the Italian publication, Napoli intend to fend off interest from the Red Devils and retain the services of their star man.
Real Madrid and PSG have also been keeping tabs on the Senegal international, who moved to the Stadio San Paolo from Genk in 2014.
The defender has established himself as one of the world’s best in his position in the last few years, and Napoli are prepared to double his salary to keep him at the club.
United,who unveiled Ole Gunnar Solskjaer as their permanent manager on Thursday, may therefore have to look elsewhere in their search for a new centre-back.