President Barack Obama condemned the violence in Libya as "outrageous ... and unacceptable" and said he was dispatching Secretary of State Hillary Clinton to Geneva for international talks aimed at stopping the violence.
Mr Obama said he was studying a "full range of options" to pressure Libyan leader Muammar Gaddafi's regime to halt attacks against Libyans as violent clashes spread throughout the North African country.
He said the options included "actions," presumably sanctions among them, that the United States could take with its allies as well as steps it might take by itself.
"We are doing everything we can to protect American citizens," Mr Obama said in brief remarks at the White House, his first public comments after days of violence in Libya.
He appeared with Mrs Clinton after the two conferred on the situation at the White House.
"We strongly condemn the use of violence in Libya," Mr Obama said. "The suffering and bloodshed is outrageous, and it is unacceptable. So are threats and orders to shoot peaceful protesters and further punish the people of Libya."
He spoke in the aftermath of uprisings in neighbouring Egypt and Tunisia. The week-old protests in Libya have been met by a far more brutal response from militiamen loyal to Mr Gaddafi.
Mr Obama broke his public silence on the violence after the US succeeded in beginning evacuations of American citizens from the chaotic situation.
Earlier, White House spokesman Jay Carney said that Mr Obama "strongly condemns" the bloodshed in Libya.
Mr Carney said that "a lot of options are under review - sanctions, other options" to end the fighting.
The president said that Mrs Clinton would attend a meeting in Geneva of the UN Human Rights Council on Monday.
"She'll hold consultations with her counterparts on events throughout the region and continue to ensure that we join with the international community to speak with one voice to the government and the people of Libya."
Mr Obama also said that William Burns, under-secretary of state for political affairs, would travel across Europe making stops to talk to allies about the developments.
Mr Obama had issued a written statement on the situation in Libya last Friday, but this was the first time he had spoken publicly about the crisis.
"We are doing everything we can to protect American citizens," Mr Obama said. "That is my highest priority. In Libya, we've urged our people to leave the country, and the State Department is assisting those in need of support."
"This is not simply a concern of the United States. The whole world is watching," he said.