While the Arab League said some progress was seen in Syria by the team of monitors who began working last week, it noted that the mission was still in its early stages.
But Sarkozy insisted that Assad "must leave power."
"The massacres being committed by the Syrian regime rightly arouse disgust and revolt in the Arab world, in France, in Europe and everywhere in the world," Sarkozy said in a New Year's address at a navy air base in Lanveoc-Poulmic, France.
The U.N. estimated several weeks ago that more than 5,000 people have been killed by Syrian security forces in the crackdown on the anti-government protests that began in March. Since that report, opposition activists say hundreds more have been killed.
The violence has drawn broad international condemnation and sanctions, but Assad remains defiant. The Arab League sent in about 100 observers a week ago to verify Syria's compliance with the organization's plan that requires the regime to remove security forces and heavy weapons from city streets, start talks with opposition leaders and free political prisoners. Syria agreed to the plan, intended to halt the crackdown, on Dec. 19.
In Washington, White House spokesman Jay Carney insisted the violence must stop. "We have made clear that if the Arab League initiative is not implemented, the international community will have to consider new measures to compel a halt to the regime's violence against its own citizens," he said.
The Arab League mission has been coming under increasing criticism by opponents of Assad's regime who say some observers lack experience. Its chief, Lt. Gen. Mohamed Ahmed Mustafa al-Dabi, raised opposition concerns because he served in key security positions under Sudanese President Omar al-Bashir, who is wanted on an international arrest warrant for crimes against humanity in Darfur.
The Arab League's deputy secretary-general, Ahmed bin Heli, said there will be a meeting Saturday to look into the first report by the head of the monitoring mission.
Arab League official Adnan al-Khudeir, who heads the operations room that the monitors report to, said the meeting will be chaired by Qatari Prime Minister Sheik Hamad Bin Jassem Bin Jabr Al Thani, a harsh critic of Assad's crackdown.
"There is noticeable progress," al-Khudeir said referring to the reports he received so far.
"It is hard to make a judgment on the mission of the monitors because they are still in the beginning," he said, adding: "We can't tell if they failed or succeeded right now."
Another official told The Associated Press that the ministerial meeting will discuss whether to pull out the monitors because of the ongoing violence. He spoke on condition of anonymity because he was not authorized to talk to the media.
No final decision will be made Saturday, but recommendations will be sent to another, high-level ministerial meeting. No date was set for that session.
On Monday, Arab League chief Nabil Elaraby acknowledged the killings have continued even with the monitors in Syria, but he insisted the mission has yielded important concessions from Damascus, such as the withdrawal of heavy weapons from cities.
"Yes, there is still shooting and yes there are still snipers," he said. "Yes, killings continue. The objective is for us to wake up in the morning and hear that no one is killed. The mission's philosophy is to protect civilians, so if one is killed, then our mission is incomplete."
Syrian opposition groups have been deeply critical of the mission, saying it is giving Assad cover for his crackdown. The Local Coordination Committees, an umbrella group of activists, says the observer mission is witnessing mainly regime-staged events, and they move about the country only with the full knowledge of the government.
Syrian dissident Omar Idilbi told The Associated Press that statements by Arab League officials "were surprising and we were shocked by what they said." Idilbi was referring to Elaraby's comments in which he said Syria's government has pulled tanks and artillery from cities and residential neighborhoods and freed some 3,500 prisoners."
"Many videos posted by activists show that tanks are still in the streets, and since the mission arrived in Syria, the regime is staging wild campaigns of arrests," he said. Still, he said, the mission's presence had advantages such as ending the regime blackout on what is going on in Syria and releasing some activists.
French Foreign Minister Alain Juppe said the regime must not be allowed to interfere with the observers on the ground.
"The conditions in which this observer mission is taking place need to be clarified," he told French television I-Tele. "Does it really have completely free access to information? We await the report that it will submit in the coming days to see more clearly."
Amateur video posted online by activists showed observers going on with their work in different parts around the country.
In the southern village of Tafas, in Daraa province, observers visited the home of a person who was said to have been killed by security forces. The mother of Khaled Majed Kiwaz told an observer at her home "he did not participate in any protest."
The woman, dressed in mourning, said her son and his paternal uncle "were shot while leaving a mosque" last month.
Activists reported more violence Tuesday.
The British-based Syrian Observatory for Human Rights said that as dozens of soldiers were defecting in the southern village of Jassem, they came under fire from security forces in a clash that killed at least 18 government troops. The Observatory said security forces later launched raids in the area, detaining more than 100 people.
The group also said security forces shot and killed three people in the restive city of Homs and three in the central province of Hama. The LCC had a higher toll, saying security forces killed four people in Homs, two in the Damascus suburbs of Kfar Batna and Arbeen, four in the central province of Hama, and one in the capital.
While most of the violence reported early in the uprising involved Syrian forces firing on unarmed protesters, there are now more frequent armed clashes between military defectors and security forces. The increasing militarization of the conflict has raised fears the country is sliding toward civil war.
The head of the observatory, Rami Abdul-Rahman, said activists will try to organize a rally Wednesday of 100,000 people in Homs modeled after Cairo's Tahrir Square. Such attempts were forcefully disperse by security forces in the past.
Syria has banned most foreign journalists from the country and prevented independent reporting, making it difficult to confirm claims from either side.