In its latest campaign aimed at creating maximum publicity, the group suggested that the flavour of the Ocean's Eleven star's perspiration - extracted from the actor's gym towel - would appeal to his fans.
Ingrid Newkirk, president of Peta, sent a letter to Clooney urging him to participate in the extraordinary venture "to spare animals from being killed for the table".
According to the Washington Post, the actor's gym towel had been offered for auction by a Peta supporter.
"I thought, 'What would make tofu more attractive to people?'... I can see people having parties to try CloFu,'" Mrs Newkirk told the newspaper.
She justified her plan by comparing Clooney-flavoured tofu to "making artificial chicken flavour for instant gravy".
But the actor rejected Peta's overtures, although he clearly found the proposition amusing.
"As a mammal, I'm offended," he joked in a statement.