Hezbollah and Iran are close allies of Assad, both accused by rebels of sending fighters to assist Syrian troops.
In Washington, Obama also took questions Tuesday about the immigration debate on Capitol Hill. Obama said that while a bill crafted by eight senators — four Democrats and four Republicans — was not the legislation he would have written, "I do think that it meets the basic criteria that I laid out from the start."
Obama also defended the implementation of the health care overhaul he signed in his first term, though he said there will be "glitches and bumps" as the sweeping law is fully implemented. He cited the unveiling Tuesday of simplified forms for people applying for insurance as an example of the administration trying to make the rollout of the law's final stages smoother.
Associated Press writers Zeina Karam in Beirut and Matthew Lee in Washington contributed to this report.