The Army Lieutenant General William Mayville said the US had no plans to expand the current air campaign in the conflict-torn country, Xinhua reported.
"US Air Force and Navy aircraft have carried out 15 air strikes since President Barack Obama Thursday authorised the military to provide humanitarian assistance to refugees on Sinjar Mountain in northern Iraq and to conduct air strikes to protect US citizens in Erbil," Mayville said.
While US air strikes have slowed ISIL's (Islamic State or IS) operational tempo and temporarily disrupted their advance toward Erbil, Mayville said the strikes are unlikely to affect ISIL's overall capabilities or its operations in other areas of Iraq and Syria.
"I think, in the immediate areas where we have focused our strikes, we have had a very temporary effect," the lieutenant general said.
He noted that the ISIL is still intent on securing and gaining territory throughout Iraq and it will continue to attack Iraqi and Kurdish security forces, Yazidis, Christians and other minorities.
The US and Britain have flown 14 humanitarian airdrops since Aug 7 to Yazidi refugees in the Sinjar Mountain in Iraq, he said.
More than 310 bundles of food, water and medical supplies have been delivered to the refugees, he added.