Instead, Dortmund chose to wait for Borussia Monchengladbach forward Marco Reus to become available, a move which was finalised in January and will be completed at the end of the season.
Lamela, one of the brightest prospects to emerge from Argentina in recent years, was linked to many European clubs last season while he was still playing for River Plate.
La Liga outfit Atletico Madrid were said to be extremely keen on him, but in the end it was Roma who secured his services in a €12million deal.
However, Zorc has since revealed BVB were very much in the running for Lamela as well, but ultimately opted against signing him as they were unsure how well he would adapt to the Bundesliga.
"There were too many uncertainties [with Lamela]," Zorc told Kicker. "With Marco Reus, we knew what we would get."
Dortmund coach Jurgen Klopp echoed Zorc's opinion that Reus represented a safer investment.
"In Marco, we had a character we could 100% evaluate," Klopp said. "That is very important.
"With Lamela, we could not do that."
Lamela has established himself as a key player for Roma despite still being only 19, already making 17 appearances in Serie A this season, while Reus has starred for Gladbach this term, scoring 13 goals in 19 league games.