The 57-year-old actor needs an aortic valve replacement, according to a news release issued by his publicist Mara Buxbaum. Williams' representatives would not give any more information on Williams' condition.
"I'm so touched by everyone's support and well wishes," Williams said in the statement. "This tour has been amazing fun and I can't wait to get back out on the road after a little tune-up."
Williams was already in Florida when he canceled four shows in the state earlier this week after experiencing shortness of breath.
Former first lady Barbara Bush, 83, this week, her doctors said.
Since September, Williams had been on the sold-out, 80-city tour, which is expected to resume in the fall, his publicist said. Tickets will be honored once the new dates are scheduled, or people can contact their place of purchase for refunds.
The Academy Award-winning actor got his start as a standup comedian in the 1970s. His high-energy act led to a guest spot on "Happy Days" as Mork from Ork and later the starring role on "Mork & Mindy."
He has appeared in dozens of feature films - both comedies and dramas - over nearly three decades. He won an Oscar for Best Supporting Actor for his role in the 1997 film "Good Will Hunting." Other notable films include "Dead Poets Society," "Hook," "Mrs. Doubtfire" and Disney's "Aladdin."