"I take responsibility," the secretary of state said during a visit to Lima, Peru, ABC News reported.
"I'm in charge of the State Department's 60,000-plus people all over the world, 275 posts."
The Associated Press, noting the impending election and Vice President Joe Biden's insistence last week that "we weren't told" about requests for extra security at the consulate, wrote that Clinton had sought to absolve the White House of any responsibility.
Clinton backed Biden's assertion, saying:
"The president and the vice president wouldn't be knowledgeable about specific decisions that are made by security professionals. They're the ones who weigh all of the threats and the risks and the needs and make a considered decision."
Administration officials initially blamed the storming of the consulate in the eastern Libyan city on a mob enraged by a U.S.-produced anti-Islamic movie, but later said it appeared to have been a terrorist attack.
Clinton said an investigation into the attack was under way into events surrounding the Sept. 11 attack, CNN reported.
"I take this very personally. So we're going to get to the bottom of it, and then we're going to do everything we can to work to prevent it from happening again, and then we're going to work to bring whoever did this to us to justice."
Ranking Senate Armed Services Committee member Sen. John McCain called Clinton's statement "a laudable gesture, especially when the White House is trying to avoid any responsibility whatsoever."
He added: "The security of Americans serving our nation everywhere in the world is ultimately the job of the commander-in-chief. The buck stops there."