The 71-year-old musician is believed to have contracted a virus, reported BBC.
A message on his website said that doctors have ordered him to have a "complete rest" and that he "hates to let people down".
"Thank you so much for your kind messages of support. I'm so very touched. Unfortunately my condition has not improved overnight. I was really hoping that I'd be feeling better today. I'm so disappointed and sorry to be letting my fans down."
He is still scheduled to perform a concert in Seoul, South Korea, on 28 May followed by 19 performances in the United States.