The 83-year-old film great had been slated to attend a fund raiser Monday for his Hole in the Wall Gang Camps for children fighting cancer and serious blood diseases, the New York Daily News said.
"He's having back problems. He has to stay off his feet for a couple of weeks," Newman's spokesman told the newspaper.
The actor, who sent a taped message to be played at the charity event, also had to scrap a planned appearance on "Late Show With David Letterman," the Daily News said.
Celebrity Families of 2014 [PHOTOS]