Carter was quoted Saturday as saying "I think as far as the adverse impact on the nation around the world, this administration has been the worst in history."
The Democrat said Bush had overseen an "overt reversal of America's basic values" as expressed by previous administrations, including that of his own farther, former President George H.W. Bush.
"I think it's sad that President Carter's reckless personal criticism is out there," White House spokesman Tony Fratto said Sunday from Texas, where Bush spent the weekend.
"I think it's unfortunate," Fratto said. "And I think he is proving to be increasingly irrelevant with these kinds of comments."
Carter made the comments to the Arkansas Democrat-Gazette in a story that appeared in the newspaper's Saturday editions.
Carter spokeswoman Deanna Congileo confirmed his comments to The Associated Press on Saturday and declined to elaborate.