Speaking to the Palm Springs Boxing Examiner, the 'School's Out' rocker criticised singer Robert Plant for pursuing an interest in folk music rather than regrouping with his former bandmates.
"They are just standing there," he said. "What is so hard?"
He continued: "[Guitarist] Jimmy Page wants to do it. [Bassist] John Paul Jones wants to do it. And they got [John] Bonham's son, who is a killer drummer. All they need is Robert Plant. But what is Robert Plant out there doing? Playing folk music! What is he doing?"
Led Zeppelin disbanded in 1980 after the death of drummer John.
The band's three remaining members collaborated with his son John for a one-off concert in 2007, but Plant later dismissed any talk of a more permanent reunion.
Last week, Steven Tyler revealed that he was approached to replace Plant as Led Zeppelin's frontman.