"We cannot turn a blind eye to images like the ones we've seen out of Syria," Obama said in his weekly address. (Agencies)
"We can't ignore chemical weapons attacks like this one, even if they happen halfway around the world. And that's why I call on Members of Congress, from both parties, to come together and stand up for the kind of world we want to live in, the kind of world we want to leave our children and future generations," he said.
Giving details of his plans for action against the embattled Syrian regime, Obama said, "There would be no American boots on the ground. Any action we take would be limited, both in time and scope, designed to deter the Syrian government from gassing its own people again and degrade its ability to do so."
He contended that the action in Syria "would not be another Iraq or Afghanistan".
The Obama administration has accused President Bashar al-Assad's forces of killing 1,429 people in a poison-gas attack in the suburbs of Damascus on August 21, a charge denied by the Syrian government.
A week ago, Obama had announced his decision to go in for a limited military strike against the Assad regime to hold it accountable for the use of chemical weapons and sought Congressional authorization for it.
Both the House of Representatives and the Senate are expected to debate and vote on the authorization resolution next week.
Obama's plans for a military strike against the Assad regime suffered a setback last week when his ally Prime Minister David Cameron's resolution seeking authorization for action suffered a shock defeat in the British Parliament. Many world leaders at the just-concluded G20 summit also did not agree with Obama's plans for a strike.
Obama and his Russian counterpart Vladimir Putin could not reach consensus yesterday when they met for "candid and constructive" talks on the sidelines of the G20 summit.
Justifying his plans for a strike, Obama said "This is not a decision I made lightly. Deciding to use military force is the most solemn decision we can make as a nation." He said this is not an open-ended intervention.
Referring to the chemical attack, Obama described it as the worst chemical weapons attack of the 21st century.
The US has presented a powerful case to the world that the Syrian government was responsible for this horrific attack on its own people, he said.
"This was not only a direct attack on human dignity; it is a serious threat to our national security. There's a reason governments representing 98 percent of the world's people have agreed to ban the use of chemical weapons," Obama said.
"Not only because they cause death and destruction in the most indiscriminate and inhumane way possible, but because they can also fall into the hands of terrorist groups who wish to do us harm," Obama said, adding that this was the reason that prompted him to ask for a military action against the Syrian regime.
"I know that the American people are weary after a decade of war, even as the war in Iraq has ended, and the war in Afghanistan is winding down. That's why we're not putting our troops in the middle of somebody else's war," Obama said.
"Failing to respond to this outrageous attack would increase the risk that chemical weapons could be used again, that they would fall into the hands of terrorists who might use them against us, and it would send a horrible signal to other nations that there would be no consequences for their use of these weapons," he said.
"All of which would pose a serious threat to our national security," Obama said.
Even as Russia and China oppose unilateral action outside UN's mandate, France has stood beside the US, calling for strong action against Syria.
"We cannot turn a blind eye to images like the ones we've seen out of Syria," Obama said in his weekly address.