The Easy Rider star, 73, was taken ill on Wednesday afternoon with a stomach complaint, his representative has confirmed.
His full condition was unknown as WENN went to press.
The actor is in the Big Apple to promote his TV show Crash, a series based on the Academy Award-winning 2004 movie.
(c) 2009 WORLD ENTERTAINMENT NEWS NETWORK LTD. All global rights reserved. No unauthorized copying or re-distributing permitted.