President Obama lamented the killing of unarmed black teenager Michael Brown in Ferguson, Mo., but appealed for calm and respect for the community's outrage Thursday as armed police and protesters clashed for the fourth straight night after the weekend shooting.

"We lost a young man, Michael Brown, in heartbreaking and tragic circumstances," Obama said during a break from his vacation on Martha's Vineyard, Mass. "He was 18 years old and his family will never hold Michael in their arms again."

"Now’s the time for healing, for peace and calm in Ferguson," he said, stressing the need for a transparent and thorough investigation into Brown's killing.

He also said that police officers in the U.S. should not be arresting journalists who are reporting on the protests.

Obama also gave an update on the latest developments in Iraq, praising the U.S. military for assisting the Kurds in fighting the Islamic State and helping thousands of Yazidis trapped on a mountain to escape while the U.S. launched airstrikes against the extremists. An unknown number of Yazidis remain stranded on the mountain, but Obama said he believed Kurdish forces would be able to help them escape without further U.S. military assistance.

"So the bottom line is the situation on the mountain has greatly improved and Americans should be very proud of our efforts," he said, noting that the U.S. troops who helped in the mission will be coming home.

He also pledged to continue to help Iraq if similar humanitarian crises erupt there in the coming weeks and months.