The 21-year-old centre-half is believed to be generating plenty of interest ahead of the winter transfer window - with Arsenal and Juventus also reported to be among his admirers.
It has been suggested that Dortmund are in pole position as they look to bring in defensive reinforcements.
The Bundesliga outfit are expected to lose Germany international Mats Hummels at the end of the season, with Barcelona said to be closing on his signature.
Schar is considered to be the ideal long-term replacement, but Zorc has attempted to steer clear of reports claiming the Swiss youngster is destined for Signal Iduna Park.
He told BILD: "The speculation about Fabian Schar being on his way to our club is one of many transfer rumours doing the rounds.
"Most of the time, these transfer rumours turn out not to be true."