The 13-time Premier League champions, who currently sit sixth in the league standings and face English top-flight rivals Liverpool in their UEFA Europa League last-16 second-leg tie at Old Trafford on Thursday night, could be drawn into making a move for the Lazio forward.
The 21-year-old, who has yet to make his senior international debut for his country, has scored five goals and provided six assists in 31 appearances for the Serie A outfit so far this season.
Diao, who spent the majority of his youth career at FC Barcelona, was also linked with Premier League rivals Arsenal and Liverpool last summer.
However the left winger told the report that, “I have a contract until 2018 and for the time being I will stay here.
“My ambition is get to play for the best teams in the world such as Barcelona, Real Madrid and Manchester United, it’s the dream of all players.”