Even as stocks continue to hit all-time highs, Warren Buffett said "they're in a zone of reasonableness."

In a live interview on "CBS This Morning" today, Buffett responded to activist investor Carl Icahn's comments, in which he said that as the Dow Jones Industrial Average touches 16,000 for the first time, stocks appear to be overpriced.

(Read more: Was Carl Icahn right to put a damper on markets?)

"I would say that they're in a zone of reasonableness," Buffett said. "Five years ago, I wrote an article for The New York Times that said they were very cheap. And every now and then, you can see that that they're very overpriced or very underpriced. Most of the time, they're in an area where maybe they're a little high, a little low, and nobody really knows exactly. They're definitely not way overpriced. They're definitely not underpriced."

Repeating his standard warning that he doesn't know what stocks will do in the "next week or next month or next year," Buffett said, "We've come back a long way from where we were five years ago, and you'll see, if you live long enough, you'll see a lot higher prices."

More specifically, Buffett predicted "five or ten years from now, I would say that they're very likely to be higher."

In the interview, done to mark American Education Week, Buffett also talked about the need for young people to establish good financial habits early in life.

—By CNBC's Alex Crippen. Follow him on Twitter: @alexcrippen