The Red Devils have reportedly offered around £21million for the German's signature ahead of a potential summer switch.
Dortmund are believed to be open to the sale, with Gundogan's contract set to expire in 2016.
There is no signature, no contract, no offer, no request and not even contact
Michael Zorc
However, sporting director Michael Zorc has played down the rumours, explaining that there has been no contact between Dortmund and United over the playmaker's transfer.
He said: "There is no signature, no contract, no offer, no request and not even contact.
"The last time I talked to Manchester United was in November 2014 and that was about a different topic."
