Dean told the network that Clinton would not have "a pass" if she decided to run, despite early polls showing her with substantial leads over other Democrats.
"There will be other people who will run," Dean said.
But Dean, whose 2004 presidential campaign derailed after a disappointing third-place finish in the Iowa caucuses his often-mocked yell, sometimes called the "Dean Scream", said he was leaning against a run at the moment.
"If you had to put a gun to my head and make me decide right now, I wouldn't," he said. "But who knows?"