"It's very difficult to talk about classified activities in an unclassified setting," Gonzales told CBS' "The Early Show" co-anchor Harry Smith.
"We tried to work as hard as we could with Congress in making sure they understood what was going on," in the executive branch Gonzales said.
On Monday, some members of Congress called for an investigation into the mysterious program, which government officials told AP allegedly sought to kill or capture suspected al Qaeda militants at close range, as opposed to using airstrikes.
Last Month, CIA Director Leon Panetta ended the program upon learning of its existence and its lack of results, and the fact that Congress had been unaware of it since its inception soon after the Sept. 11, 2001, terror attacks, according to one official with direct knowledge of the plan told AP.
Gonzales' hesitancy to talk may stem from a 2008 Justice Department report that charged he mishandled highly classified and sensitive documents relating to the Bush administration's counterterrorism plans.
He resigned amid controversy in 2007 after holding the attorney general post for more than two years. Prior to being attorney general, Gonzales served as President Bush's White House Counsel.
Questions about the CIA program followed a discussion about Supreme Court nominee Sonia Sotomayor's confirmation hearings on "The Early Show."
Gonzales, himself a former Texas State Supreme Court judge, said a good justice is "sensitive" to his or her biases.
"That should be the reality in every case, not an aspiration," Gonzales said.