US President Barack Obama on Saturday vowed to continue air strikes against Iraqi jihadists if needed to protect US diplomats and military advisors.

Speaking in his weekly address, Obama said that he had authorized the strikes in Iraq to protect US personnel serving in the northern city of Arbil. "And, if necessary, that's what we will continue to do," he said.

Obama said he had also authorized a "humanitarian effort" to help displaced civilians trapped by jihadists on Mount Sinjar in northern Iraq.

Thousands of Yazidis, a Kurdish-speaking minority, fled their homes when militants attacked the town of Sinjar and many have since been stranded in the nearby mountain range with no food and water.

"The thousands -- perhaps tens of thousands -- of Iraqi men, women and children who fled to that mountain were starving and dying of thirst. The food and water we airdropped will help them survive," Obama said.

"I've also approved targeted American airstrikes to help Iraqi forces break the siege and rescue these families."

Obama emphasized that the United States "cannot and should not intervene every time there's a crisis in the world.

"But when there's a situation like the one on this mountain -- when countless innocent people are facing a massacre, and when we have the ability to help prevent it -- the United States can't just look away. That's not who we are. We're Americans. We act. We lead. And that's what we're going to do on that mountain."

As head of the US military, "I will not allow the United States to be dragged into fighting another war in Iraq. American combat troops will not be returning to fight in Iraq, because there's no American military solution to the larger crisis there.

"What we will do is continue our broader strategy in Iraq. We will protect our citizens. We will work with the international community to address this humanitarian crisis. We'll help prevent these terrorists from having a permanent safe haven from which to attack America."

The United States will also "continue to urge Iraqi communities to reconcile, come together and fight back against these terrorists so the people of Iraq have the opportunity for a better future-the opportunity for which so many Americans gave their lives in Iraq in a long and hard war," Obama said.

The first US bombings struck IS positions and at least one convoy of vehicles carrying militants west of Arbil.

The Pentagon also said late Friday that cargo planes escorted by combat jets made a second air drop of food and water to "thousands of Iraqi citizens" threatened by the jihadists on Mount Sinjar.