Carney did not offer specific proposals or a timeline. He said President Barack Obama will meet with law enforcement officials and mental health professionals in coming weeks.
New York Mayor Michael Bloomberg, flanked by shooting survivors and relatives of victims of gunfire around the country, pressed Obama and Congress to toughen gun laws and tighten enforcement after the Newtown massacre.
"If this doesn't do it," he asked, "what is going to?"
At least one senator, Virginia Democrat Mark Warner, said Monday that the attack in Newtown has led him to rethink his opposition to the ban on assault weapons.
West Virginia Sen. Joe Manchin, a Democrat who is an avid hunter and lifelong member of the National Rifle Association, said it's time to move beyond the political rhetoric and begin an honest discussion about reasonable restrictions on guns.
"This is bigger than just about guns," he added. "It's about how we treat people with mental illness, how we intervene, how we get them the care they need, how we protect our schools. It's just so sad."