Yemen's president has apologized to President Barack Obama for the attack on the U.S. Embassy in Sanaa, the Yemeni capital, by a mob angry over an anti-Islam film.

The U.S. Embassy in Yemen says nobody was harmed in Thursday's assault. "All embassy personnel are safe and accounted for," spokesman Lou Fintor said.

President Abed Rabbo Mansour Hadi also ordered an investigation into the attack. Several hundred protesters stormed the embassy's compound, brought down the U.S. flag in the courtyard, burned it and replaced it with a black, Islamist banner.

Hadi avowed to bring the culprits to justice, saying the attack by a "rowdy crowd" was part of a conspiracy to derail Yemen's close relations with Washington.

Chanting "death to America," hundreds of protesters angered by an anti-Islam film stormed the U.S. Embassy compound in Yemen's capital and burned the American flag on Thursday, the latest in a series of attacks on American diplomatic missions in the Middle East.

Hundreds of angry demonstrators burned the American flag and stormed the U.S. Embassy compound in Yemen Thursday.

The protesters were able to breach a normally tight security perimeter around the Embassy and get into the grounds.

A senior Obama administration told ABC News the protests appear to be motivated by an anti-Muslim film, just like in Cairo, Egypt this week.

The film’s 13-minute trailer that was posted to YouTube depicts the prophet Muhammad as a womanizer and a fraud.

In Cairo, protesters again clashed with security forces outside the U.S. Embassy as riot police fired tear gas.

Overnight, the protesters broke through a barbed wire barrier and burned tires near the embassy. They smashed windows before breaking through the main gate.  Security guards stopped them with warning shots.

“We certainly hope and expect that there will be steps to avoid violence and prevent escalation of protests into violence,” said Secretary of State Hillary Clinton.

But in Benghazi, Libya, it was a very different scene.  People took to the streets not to protest, but to grieve Wednesday.

On Tuesday, militants stormed the U.S. consulate during a nearly five-hour firefight that left four Americans dead, including the U.S. Ambassador to Libya, Chris Stevens.

“It’s especially tragic that Chris Stevens died in Benghazi, because it is a city that he helped to save,” said Obama.

Obama called the presidents of Egypt and Libya Wednesday night.  The White House said he urged the two leaders to keep working with the U.S. to ensure the safety of diplomatic personnel. 

Actress said director lied

An actress in the anti-Muslim movie that is blamed for sparking the violence said the director, Sam Bacile, lied to her.

Bacile’s real name is Nakoula Basseley Nakoula, officials said. He describes himself as Anisreaeli-American real estate developer and he is now in hiding.

Cindy Lee Garcia said the movie was supposed to be about life 2,000 years ago and that there was no mention of Muhammad.

She said she would never hurt anybody and wants her name cleared.

“When I found out this movie had caused all this havoc, I called Sam and asked him why, “What happened? Why did he do this?’ And he said, ‘Why did you do this to us, to me and to us?' And he said, 'Tell the world it wasn’t you that did it. It was me the one who write the script, because I am tired of these radical Muslims running around killing everyone,’” Garcia said.

Local expert concerned about response to violence

Channel 9 spoke to a professor at Davidson College Thursday who used to live in Egypt.

Professor Jonathan Berkey said he is a little concerned about how long it took the Egyptian government to respond to the riots.

He has not spoken with his friends in Egypt since the unrest. 

Berkey said the general feeling among them is excitement over the broader political change that has been happening, but some apprehension about what the future holds.

This unrest makes the apprehension a little greater, Berkey said.

“It makes the whole thing more unstable and significant. One of the dangers is episodes like this.  With this offensive film being produced gives the radicals, the al-Qaeda types an opening,” Berkey said.

The Associated Press contributed to this report.