The US remains "one indispensable nation" in the Middle East, Xinhua quoted Obama as telling CNN.
Asked about claims of chemical weapons use in Syria, Obama said officials were "right now gathering information" and that "what we've seen indicates that this is clearly a big event of grave concern".
Saying the US was pushing "to prompt better action" from the UN, and was calling on the Syrian government to allow an investigation at the site of the alleged attack outside Damascus," Obama said "core national interests" of the US were now involved in Syria's civil war.
He said the US needed to make "sure that weapons of mass destruction are not proliferating, as well as needing to protect our allies, our bases in the region".
But he was cautious on whether to intervene militarily in Syria, saying "if the US goes in and attacks another country without a UN mandate and without clear evidence that can be presented, then there are questions in terms of whether international law supports it".
The costs of military action "have to take those into account as we try to work within an international framework to do everything we can to see Assad ousted", Obama said.
On the subject of whether to cancel military aid to Egypt, Obama reasoned "the aid itself may not reverse what the interim government does".
"What most Americans would say is that we have to be very careful about being seen as aiding and abetting actions that we think run contrary to our values and our ideals."
The president said the administration was currently "doing a full evaluation of the US-Egyptian relationship", and that there was "no doubt that we can't return to business as usual, given what's happened".
Also Friday, the Wall Street Journal indicated that the Pentagon had begun updating target lists for possible air strikes on a range of Syrian government and military installations.
The New York Times also reported that senior officials from the Pentagon, the State Department and the intelligence agencies met for three and a half hours at the White House Thursday to deliberate over options.
--IANS (Posted on 23-08-2013)