In an interview with CNN, Holder criticized Congress for failing to pass stricter background checks for firearms purchases following massacres in Newtown, Conn., and elsewhere.
"Yes, we've failed," he said.
"It can't be the new normal," Holder said. "It cannot be something that we accept."
Four days after TSA agent Gerardo Hernandez, 39, was killed and several others were wounded in a shooting at Los Angeles International Airport, Holder said he is concerned about the possibility for more so-called lone wolf attacks by "individuals who get radicalized in a variety of ways, sometimes self-radicalized."
There have been reports the LAX shooter was in possession of anti-government materials at the time of the shooting Friday.
However, Holder said he does not think TSA agents should be armed.
"Now, that doesn't mean that we shouldn't review the measures that are in place to keep people safe from the time that they get out of their cars and go into the terminals," he said.
Holder said he opposes clemency for former National Security Agency contractor Edward Snowden, who has been granted asylum in Russia after releasing massive amounts of classified data on U.S. intelligence gathering.
"I think that he has clearly broken the law and harmed the nation that he claims to have loved," the attorney general said.
However, he acknowledged the fallout from Snowden's actions helped start a re-evaluation of "how do we safeguard privacy and keep the American people safe."