Graham has charged the Boston Marathon bombing and the attack on the U.S. consulate in Benghazi, Libya, are examples of a failure in U.S. intelligence gathering.
At a White House news conference, Obama said both incidents are being fully investigated and every step that was taken beforehand will be reviewed.
"Based on what I've seen so far, the FBI performed its duties, the Department of Homeland Security did what it's supposed to be doing. ... Because of the pressure we have put on al-Qaida ... one of the dangers we now face are self-radicalized individuals ... who may not be part of any network [who decide to attack]. ... Those are in some ways more difficult to prevent," Obama said.