Golden, Colorado: The White House said Thursday that it was doing everything it could to protect its diplomats in Yemen, after a mob breached the embassy wall as fury spread over a US-produced film mocking Islam.
"We are doing everything we can to protect safety and security of personnel," White House spokesman Jay Carney said, adding that President Abdrabuh Mansur Hadi had pledged his government would not tolerate violence.
The State Department said all of the US staff at the embassy in Yemen, a hot front on the US campaign against Al-Qaeda in the Arabian Peninsula, were safe.
"We are obviously doing what we can with the Yemenis to restore security there. All of our personnel are safe and accounted for," State Department spokeswoman Victoria Nuland told journalists.
Hadi earlier publicly apologized to US President Barack Obama and the American people for the acts of a "mob" and ordered a probe.
Yemeni police used water cannon and fired warning shots to expel protesters who breached the perimeter wall of the embassy and at least four people were killed as police battled to prevent any new incursion.
"There was a small breach of the compound perimeter but there was no breach of the embassy buildings," Nuland said.
The protests came after US and Libyan officials said they were probing a mob attack on the US consulate in Benghazi that killed the ambassador and three other US officials on Tuesday.
The unrest in Libya, Egypt and Yemen was blamed on outrage over an amateur, American-made film -- which mocks Islam's revered prophet Mohammed and was circulated on YouTube.
Carney echoed Secretary of State Hillary Clinton's comments when he said the US government found the movie "disgusting and reprehensible" and noted America's founding tolerance for religious freedom, including that of Muslims.
But he also explained that the Obama administration had no power under America's founding principles guaranteeing free speech to stop the release of the film.
"We understand that it is hard for some people around the world to understand why the United States does not prevent movies like this from seeing the light of day," Carney said. "That's impossible to do."
"Furthermore, and more importantly, our country has a long tradition of free expression that is protected by law," he said.
"Our government does not and cannot stop individual citizens from expressing their views.
"Those of us who care about religious tolerance, respect religious beliefs must not allow a tiny minority of people to provoke conflict between different religions, cultures and countries."