"Arsenal is in a goalkeeper emergency in the moment," the 41-year-old said, "so I'll happily help out."
Lehmann is believed to be wanted as an emergency signing, after injuries reduced Arsenal to one senior goalkeeper.
Manuel Almunia played in the FA Cup sixth round match against Manchester United, with 19-year-old James Shea on the bench after injuries ruled out Wojciech Szczesny, Lukasz Fabianski and Vito Mannone.
Lehmann is currently based at the Gunners' London Colney training HQ on a coaching course, but Sky Sports claim he is discussing a short-term deal with the club.
The German represented Arsenal from 2003 to 2008, clocking up 199 appearances before leaving for Stuttgart having lost his place in the team to Almunia.
On Sunday, he told Bild newspaper: "I am in London and so far have heard nothing of such plans, but you never know."