"I know he damaged the country and the Obama administration will deal with it," Mr Bush told CNN in an interview to be broadcast in full later today.
"I think he damaged the security of the country," added Mr Bush, who spoke to the network in Zambia, where he and wife Laura Bush were traveling on a humanitarian mission.
"I put the program in place to protect the country and one of the certainties is civil liberties were guaranteed," Mr Bush said.
"Ultimately, history will judge the decisions I made. I won't be around because it's going to take a while for the objective historians to show up. And so I'm pretty comfortable with it. I did what I did. I know the spirit in which I did it," he said.
Snowden, a former contractor at the National Security Agency, sparked a furor by disclosing details of vast phone and Internet surveillance to the media.
He initially surfaced in Hong Kong before fleeing to Russia after US espionage charges were filed against him.
He is now believed to be holed up in a Moscow airport hotel and seeking asylum in Ecuador.
The top secret spy programs, set up by the Bush administration in the wake of the September 11, 2001 attacks, have continued under Mr Obama, who says he has sought to balance national security and privacy.