"We're not considering any open ended commitment. We're not considering any boots on the ground approach," Obama said during an appearance at the White House following a meeting with Baltic leaders.
Obama said he has not made any final decisions and still is consulting with Congress and U.S. allies.
The comments came as the White House released an unclassified intelligence assessment of the Aug. 21 attack that left more than 1,400 dead, including more than 400 children, in the suburbs of Damascus.
Obama, calling images from Syria in the wake of the attack "horrific," said the use of chemical weapons presents a "challenge to the world."
"We cannot accept a world where women and children -- innocent civilians -- are gassed on a grand scale," Obama said, adding the action "challenges our national interests" and threatens U.S. allies.
He said if the action goes unanswered, it will present the risk of an increased use of chemical weapons in the future and that such weapons could fall into the hands of terrorists.
"The world has an obligation that we maintain the norm against the use of chemical weapons," he said. "I have not made a final decision ... [but the world has an obligation] to enforce that norm."
Obama said he is looking at a "wide range" of options but a "narrow, targeted" action is most likely.
Obama said many people think something should be done about the chemical weapons attack "but nobody wants to do it."
"There is a certain weariness, given Afghanistan. There is a certain suspicion of any military action post-Iraq. And I very much appreciate that. ... It's important for us to recognize that when over a thousand people are killed, including hundreds of innocent children, through the use of a weapon that 98 [percent] or 99 percent of humanity says should not be used even in war, and there is no action, then we're sending a signal ... . That is a danger to our national security."
U.S. Secretary of State John Kerry earlier said the world is watching to see what the United States will do and U.S. credibility rests on it.