In the Washington Post article, Panetta reacted angrily to suggestions "that those who gave their lives somehow brought it upon themselves because of poor tradecraft".
"This was not a question of trusting a potential intelligence asset, even one who had provided information that we could verify independently. It is never that simple, and no one ignored the hazards," Panetta said.
There has been much speculation since the attack that al-Balawi had been allowed to bypass security checkpoints at the base because of his value as an intelligence asset.
The Washington Post said the CIA had been planning to speak with the bomber about possible ways to target Ayman al-Zawahiri, al-Qaeda's second-in-command.
Robert Baer, a former CIA operative, said that even if the US agents were planning to search al-Balawi they possibly made a mistake in allowing him to enter the base first.
"The only reason this man should have been brought into a base was to pass him through a metal detector, apparently he wasn't," he told Al Jazeera from from Berkeley in California.
"He was about to be searched and people were watching him, anybody who has been around suicide bombings knows you do not want to do this in an open area when people are close by.
"The pellets in these bombs go quite a distance."
In a video released to Al Jazeera on Saturday, al-Balawi said he was carrying out the attack in response to the death of Baitullah Mehsud, the Pakistani Taliban leader who was killed by a US drone in August last year.
"We say that we will never forget the blood of our Emir Baitullah Mehsud, God's mercy on him," al-Balawi said as he appeared with Hakimullah Mehsud, the Pakistani Taliban leader who succeeded baitullah Mehsud.
"To retaliate for his death in the United States and outside the United States will remain an obligation on all emigrants who were harboured by Baitullah Mehsud."
Khalil al-Balawi, the bomber's father, speaking from his home in the Jordanian capital, Amman, confirmed that it showed his son.
"We are not surprised, fighting the arrogant, unjust, haughty and tyrant American who kills civilians and innocent people makes the whole Islamic world hate America ... I say that Hammam sacrificed his body and soul for the oppressed," he said.
But Khalil al-Balawi also criticised intelligence officials for what he said was a change in his son's behaviour.
"I blame the agencies that recruited him, and changed him," he said.
"They changed him. They turned him from a human, a doctor, to a person with a heart full of negative and hostile emotions toward others."