The official, speaking on condition of anonymity, was commenting on a report in The New York Times that Obama was weighing either air strikes or humanitarian airdrops to help 40,000 religious minorities trapped on an Iraqi mountaintop under threat from the militants.
White House spokesman Josh Earnest told reporters earlier that Obama had met members of his national security team on Thursday (local time). Earnest declined to say whether US military intervention in Iraq was being considered.
Any airstrikes would represent the first combat action by the United States in Iraq since it pulled out the last of its troops in 2011 to end eight years of war. Earlier this year the United States sent in a small number of military advisers to help the Iraqi government address the threat of the Islamic militant offensive.
Earnest said Obama had made clear in the past that any US military action would be "very limited in scope," would not involve putting troops on the ground, and should be closely tied to Iraqi political reforms, which Washington has demanded.
"We're working intensively with the government of Iraq - the Iraqi security forces and the Kurdish authorities in the immediate area to support their efforts to address the humanitarian situation in Sinjar," Earnest said.
Although he declined to directly address the issue of possible US action at Sinjar, Earnest stressed the strict limits of any US military involvement in Iraq. "There are no American military solutions to the problems in Iraq," he said.
The Islamic State's Sunni militants, an offshoot of al Qaeda who have swept across northwestern Iraq in recent weeks, have come within a 30-minute drive of the Kurdish capital Arbil.
US SAYS BAGHDAD RESPONSIBLE
Some of the many thousands trapped on Sinjar mountain have been rescued in the past 24 hours, a spokesman for the U.N. Office for the Co-ordination of Humanitarian Affairs said earlier, adding that 200,000 had fled the fighting.
Earnest said the responsibility for the humanitarian crisis in Iraq, including that on Sinjar mountain, lay with the Iraqi leaders who had failed to create a united government to address the interests of the country's Shi'ites, Sunnis and Kurds.
The Islamist fighters, who have killed many thousands and declared a caliphate in the Iraqi area they conquered, are now threatening Kurdistan, previously considered a bastion of stability in a country ravaged by conflict.
Bernadette Meehan, spokeswoman for Obama's National Security Council, told Reuters on Wednesday that any provision of US weapons to the Kurds "must be co-ordinated with central government authorities, in Iraq and elsewhere."
But she added that given the threat from the Islamic State, "the United States will continue to engage with Baghdad and Arbil to enhance cooperation on the security front and other issues."
