The 17-minute audio recording features Adam Gadahn, or "Azzam the American," CNN reported. It was posted on the Internet late Friday.
"We express our condolences to the families of the Muslim men, women and children killed in these criminal acts and we ask Allah to have mercy on those killed and accept them as shohadaa (martyrs)," Gadahn says. "We also express the same in regard to the unintended Muslim victims of the mujahedeen's operations against the crusaders and their allies and puppets, and to the countless faceless and nameless Muslim victims of the murderous crusades."
The video appears to be part of a damage-control effort by al-Qaida, CNN said. The group's attacks have angered many in Pakistan and Afghanistan.
Gadahn, 31, of partly Jewish descent, was home-schooled in Southern California by parents who had become devout Christians. He converted to Islam in his late teens and moved to Pakistan.