Pulisic admitted that he could play in the Premier League "one day" amid speculation linking him with a move to Chelsea, while Liverpool and Tottenham are also said to be interested in signing the midfielder.
United States international Pulisic has made just four Bundesliga starts for Dortmund having struggled with injuries so far this season but Zorc said he is very much in manager Lucien Favre's plans.
Responding to suggestions that Pulisic could be a target for Premier League clubs in the January transfer window, Zorc told Kicker: "We've known these rumours for many years.
"We're planning to go with them until the end of the season."
Pulisic's current deal runs until the middle of 2020 and a transfer at the end of the 2018-19 season appears a possibility.
Despite facing a struggle to keep hold of one of their most promising players, Zorc said: "We will still need Christian significantly."