Former New York Stock Exchange chairman Richard Grasso says he may run for mayor — if it’s against his old enemy, Eliot Spitzer.

Grasso says he’ll run in 2013 if Spitzer, who battled him as state attorney general, is in the field and Police Commissioner Raymond Kelly isn’t.

He spoke Thursday night at Wagner College on Staten Island. Grasso said he’d heard Spitzer is considering running as an independent.

Spitzer, a Democrat, refused to comment.

In 2004, Spitzer tried unsuccessfully to block much of Grasso’s $187.5 million compensation package from the New York Stock Exchange.