The 27-year-old is thought to be on the radar of the Premier League champions and big-spending Monaco, but no offers have been made yet.
And Marchisio insists that he is unsure where his future lies, although he is flattered by talk of a potential move to Manchester.
"There are things to be proud of, but I am not sure if they are true," Marchisio told Gazzetta dello Sport.
"I have not heard from anyone at Manchester United or Monaco.
"When I talk with my club everything will become clearer."
Marchisio is in Rio de Janeiro with Italy at the Confederations Cup, and is remaining focused on the task at hand.
He said: "Now I only think of the Confederations Cup. That is all that is important at the moment."