The snail-paced peace talks, which started last month with Brahimi serving as an intermediary between the two delegations sitting in the same room, have failed to produce an agreement on a first step for resolving the conflict, which has dragged on for nearly three years.
More than 140,000 Syrians have died since March 2011, according to the Syrian Observatory for Human Rights, a London-based opposition group.
About half of them were civilians, and more than 7,000 were children and more than 5,000 were women, it said.
It put Syrian military losses at more than 30,000 and pro-regime elements at more than 20,000. Those figures do not include the 18,000 Syrians who were jailed and are missing, it said.
Relief for besieged city
Brahimi said he would consult next with U.N. Secretary-General Ban Ki-moon and called upon him to hold discussions with U.S. Secretary of State John Kerry and Russian Foreign Minster Sergey Lavrov.
Brahimi said he would also likely brief the permanent members of the U.N. Security Council, known as the P5 -- the United States, Russia, Britain, France and China -- and the full Security Council.
The talks' only sign of progress has been a cease-fire to allow some evacuations from and aid relief to the besieged city of Homs.
U.N. Emergency Relief Coordinator Valerie Amos said Friday that 1,400 people were evacuated from the Old City of Homs and 2,500 still there got relief supplies, but she lamented the bleak humanitarian situation that prevails throughout the country.
"The little that has been achieved in Homs," Brahimi said, has given the Syrian people hope that they might finally be "coming out of this horrible crisis they are in."
But the warring sides are still far apart.
Opposition: We want progress, not delaying tactics
Brahimi said he hoped that, after a period of reflection, the two sides would return to the table "ready to engage seriously" over how to implement the so-called Geneva communique that led to the talks. It calls for ending the conflict and establishing a transitional government.
The opposition has proposed a transitional government that would oversee a halt in the fighting, releasing prisoners of conscience, maintaining law and order, bringing to justice those responsible for violence and protecting human rights.
Its plan excludes al-Assad from continued leadership, an outcome unacceptable to the longtime Syrian leader.
But Syrian Deputy Foreign Minister Faisal Makdad said Friday that the opposition has "an unrealistic agenda," and he insisted the first step must be "stopping the violence and ending terrorism."
The government refers to the rebels as foreign-backed terrorists, so Makdad's stance in essence calls for the opposition to unilaterally lay down its arms.
"We confirm we are willing to discuss the issue of the transitional government after we reach an agreement regarding ending terrorism," he said.
French diplomat slams regime, praises opposition
Laurent Fabius, the French foreign minister, blamed the Syrian government for the lack of advancement.