President Obama concerned about Ferguson, Missouri violence; says U.S. broke Iraq militants' mountain siege

President Barack Obama pauses while speaking about the situations in Iraq and in Ferguson, Mo. (AP)

EDGARTOWN, Mass. (AP/ABC News) - President Barack Obama said Thursday that there is no excuse for the use of excessive force by police in the tense aftermath of the shooting death of an unarmed black teenager in Ferguson, Missouri, and no excuse for violence against the police.

In brief remarks near his vacation spot in Martha's Vineyard, Obama said he wants an open and transparent investigation of the shooting death of 18-year-old Michael Brown, so that justice is done.

He also said police shouldn't be arresting and bullying journalists who are doing their jobs. Two reporters were taken into custody and briefly jailed Wednesday evening in the St. Louis suburb amid clashes between protesters. There were reports of Molotov cocktails, tear gas and rubber bullets being used.

"I know that emotions are raw right now in Ferguson," Obama said in a news conference. "There is never an excuse for violence against the police or for those who would use this tragedy as a cover for vandalism or looting. ... There is also no excuse for police to use excessive force against peaceful protests or to throw protesters in jail."

Meanwhile, Obama said the U.S. had broken Islamic militants' siege on Iraq's Sinjar Mountain, but added that airstrikes would continue.

Obama said U.S. operations helped thousands of civilians flee down the mountain, and indicated it was unlikely that more airdrops of food and water would be needed.

The Islamic State group's advance in Iraq has driven thousands of people from their homes.

These refugees faced “a terrible choice: starve on the mountain or be slaughtered on the ground. That’s when America came to help,” Obama said.

Two U.S. officials said that roughly 4,500 people remain atop northern Sinjar Mountain, and nearly half are herders who lived there before the siege and have no interest in being evacuated.

The officials said a U.S. team who spent Wednesday on the mountaintop reported numbers far smaller and circumstances less dire than feared.

“The bottom line is, is that the situation on the mountain has greatly improved and Americans should be very proud of our efforts,”Obama said, adding “I could not be prouder of the men and women of our military who carried out this humanitarian operation almost flawlessly.”

U.S. airdrops delivered more than 114,000 meals and 35,000 gallons of fresh water to refugees, Obama said