The president's pledge comes as key House Republicans restated their firm opposition to enacting any new limits on firearms or ammunition, setting up the possibility of a philosophical clash over the Second Amendment early in Obama's second term.
"This time, the words need to lead to action," Obama said, referring to outrage to previous mass shootings that eventually led to little or no legislative changes.
But he said the proposals would not be just about weapons.
"We are going to need to work on making access to mental healthcare at least as easy as access to guns," he said.
During the appearance in the White House briefing room, the president said he has directed Vice President Joe Biden to lead an interagency effort to develop in the next several weeks what the White House says will be a multi-faceted approach to preventing similar mass shootings and the many other gun deaths that occur each year.
Obama, flanked by Biden, did not offer any specifics about the proposals. But he promised to confront the long-standing opposition in Congress that has previously blocked more aggressive gun-control measures.
"I will use all the powers of this office to help advance efforts aimed at preventing more tragedies like this," Obama said. "It won't be easy, but that can't be an excuse not to try."
The president said Biden's group will make proposals for new laws and actions in January, and he said those will be "proposals that I then intend to push." Obama said of Biden's effort: "This is not some Washington commission" that will take six months and be shelved.
He said the "conversation has to continue. But this time, the words need to lead to action. I urge the new Congress to hold votes on these new measures next year, in a timely manner."
When asked about the fiscal negotiations, Obama said he would be reaching out to congressional leaders of both sides to try to move the talks forward even as House Republicans were preparing to vote on their alternative proposals.
The deaths Friday of 27 people, 20 of them children, in a school shooting in Newtown, Conn., appears to have softened opposition to gun control among some Democratic lawmakers, particularly in the Senate. But there has been little indication that Republicans who control the House of Representatives are willing to accept new restrictions.
Rep. Bob Goodlatte, R-Va., the incoming chairman of the House Judiciary Committee, said Tuesday that he has no interest in moving any sort of gun control legislation through the chamber.
"We're going to take a look at what happened there and what can be done to help avoid it in the future, but gun control is not going to be something that I would support," Goodlatte told the Roll Call newspaper.
Rep. Howard Coble, R-N.C., said in an interview that he thought the talk of gun control was "probably a rush to judgment" that missed the real issue.
"I think it's more of a mental health problem than a gun problem right now," he said in an interview. "Traditionally states that enact rigid, inflexible gun laws do not show a corresponding diminishment in crime. I think we need to be careful there. I think we need to look at how the mentally impaired get access to firearms."
While he said he would want to study any proposal made by the president, he suspected the rest of the Judiciary Committee majority would agree with his views.
"I suspect it would be pretty much what Chairman Goodlatte told you and what I told you," he said.
The president promised during a speech at a memorial service in Newtown on Sunday to "use whatever power this office holds" to prevent more similar tragedies. He offered no specific prescriptions; aides have since said that he is looking at tighter gun regulations including a ban on assault weapons and possibly on high-capacity ammunition clips.
But they said he also wants to examine other factors, including the mental health system, education and possibly cultural dynamics, not just gun legislation.
"He wants to expand the conversation beyond those specific areas of legislation to look at other ways we can address this problem," Jay Carney, the White House press secretary, said Tuesday.
One senior Republican signaled openness to that kind of approach.
"As the president said, no set of laws will prevent every future horrific act of violence or eliminate evil from our society, but we can do better," Rep. Jim Sensenbrenner of Wisconsin said in an emailed response to questions about the subject.
Sensenbrenner noted that he co-sponsored the Brady gun-control bill in the 1990s.
"Our country must also grapple with difficult questions about the identification and care of individuals with mental illnesses," he said. "I look forward to having an honest debate about these issues."
Gun-control advocates have urged the White House and lawmakers to move rapidly to enact new gun-control measures before the memory of the killings in Connecticut fades from the public's consciousness. Sen. Dianne Feinstein, D-Calif., has said she intends to introduce a new ban on assault weapons and high-capacity magazines on the first day of the next Congress in January.
Obama said he is "betting" that the majority of Americans, including gun-owners, will not forget the deaths of the children and the teachers in Newtown.
"There's no law or set of laws that can prevent every senseless act of violence in our society," he said. But he added: "The fact that this problem is complex can no longer be an excuse for doing nothing."