Goal confirmed in late May that the Greece international defender had emerged as a top target for new Gunners boss Unai Emery.
Arsenal’s head of recruitment, Sven Mislintat, has worked with the 30-year-old before in Germany and believes he would be a useful addition at Emirates Stadium.
No agreement has been completed as yet, though, with talks having now dragged on for over a month.
Zorc told Revier Sport: “It looks like he will go there, that's right. But things are not completely finalised yet.
“And I will not work with you now and talk about the rumour mill, which includes 27 new BVB players since the end of May.
“In the meantime, we are having fun ourselves and planning. We have clear ideas and I am very sure that we will put together a very good team.
“This will not necessarily be the case until the start of the season, because the coach wants to make an impression on the players who are under contract with us.”
Arsenal have already brought two fresh faces onto their books this summer, with veteran Swiss full-back Stephan Lichtsteiner the first to arrive after reaching the end of his contract at Juventus.
Bernd Leno has also been acquired to bolster the goalkeeping ranks, with the Germany international making a €22million (£19.2m/$25m) move from Bayer Leverkusen.
Emery has hinted that there will be more arrivals to come, with there a desire on his part to strengthen a squad inherited from Arsene Wenger.
He said: “I believe we can grow with the players we have.
“The objective is to work hard together and with these talented players.