"We've condemned that violence," Rice told "Meet the Press" on NBC. "Our view is that in Libya as throughout the region peaceful protests need to be respected."
The Arab League said it was following with great concern the demonstrations in Arab countries and called for "the immediate halt of all acts of violence and to refrain from using force against the peaceful demonstrations."
In Cairo, Libya's Arab League representative Abdel-Monem al-Houni said he told the Foreign Ministry in Tripoli that he had "resigned from all his duties and joined the popular revolution."
"As a Libyan citizen, I absolutely cannot be quiet about these crimes," he said, adding that he had renounced all links to the regime because of "my complete devotion to my people."
Al-Houni was part of the group that carried out the coup in 1969 that brought Gadhafi to power. He later fell out with the Libyan leader, but they reconciled in 2000. Gadhafi then named him to the Arab League post.
The violence followed the same pattern as the Saturday crackdown, when witnesses said forces loyal to Gadhafi attacked mourners at a funeral for anti-government protesters. They were burying 35 marchers who were slain Friday by government forces.
Sunday's defiant mourners chanted: "The people demand the removal of the regime," which became a mantra for protesters in Egypt and Tunisia.
On Saturday, witnesses said a mix of special commandos, foreign mercenaries and Gadhafi loyalists assaulted demonstrators in Benghazi with knives, assault rifles and other heavy weapons.
The Libyan news agency said authorities arrested "dozens of foreign elements trained to strike at Libya's stability and security." It said an investigation already was under way. It also said authorities were not ruling out that those elements were connected to what it called an Israeli plot to destabilize countries in North Africa, including Libya, as well as Lebanon and Iran.