The Bundesliga club claimed they were close to signing the goalkeeper from Arsenal but Gunners boss Wenger denied that a deal was done.
Dortmund spokesman Joseph Schneck said: "It is true that we have come to terms financially but we are still waiting for him to iron out a few things that are important for him, like personal matters.
"Then we hope he will join us.
"But it would be too early to confirm that he'll come."
Die Bild newspaper reported on their website that a deal had been done, quoting Dortmund sports director Michael Zorc as saying: "Between us and Lehmann everything has been settled.
"We are in constant contact. We have even come to terms financially."
But Schneck insisted the newspaper had jumped the gun.
"Jens Lehmann will not be here in the next one or two days," he added.
But Wenger said: "It's not true. Not for Jens and not for us.
"I deny that Jens has agreed personal terms with Dortmund and I deny that we have an agreement with Dortmund."