United Nations and Arab League envoy Lakhdar Brahimi has said the crisis in Syria is "bad and it is getting worse."
He was speaking after talks in Moscow with Russian Foreign Minister Sergei Lavrov.
Brahimi said he will not be discouraged by the failure of the cease-fire he proposed.
"We shall continue to work as hard as we possibly can and [work] in cooperation with everybody, inside Syria and outside of Syria, to bring the level of violence down, put an end to it, and launch Syria on the road to building the new Syria," he said.
The truce was supposed to start on October 26 and last over the four-day Eid al-Adha Muslim religious holiday. But it never took hold, with Syrian government forces and rebels fighting against President Bashar al-Assad's regime blaming each other for the fighting.
Also on October 29, Syrian state television said 10 people were killed by what it called a "terrorist" car bombing in Damascus.
Lakhdar Brahimi: "We shall continue to work as hard as we possibly can."
Syrian activists say hundreds of people have been killed in fighting in Syria since October 26.
The truce proposed by Brahimi was the latest UN attempt to halt the Syria violence.
In April, Brahimi's predecessor, former UN Secretary-General Kofi Annan, proposed an open-ended cease-fire to be followed by political talks, but the plan collapsed.
At a news conference with Brahimi, Lavrov said the international community should speak with one voice regarding the Syrian violence.
"It is necessary that all foreign actors use their influence on the different Syrian groups, either governmental or opposition -- and the opposition is far from homogeneous -- and send the same message to them, not encourage any particular side to continue the violence and bloodshed, but persuade them to declare an immediate cease-fire and begin a political process," Lavrov said.
The Chinese Foreign Ministry says Brahimi will travel to Beijing on October 30 but did not provide details about whom he would meet during his two-day visit.
Russia and China have vetoed three UN resolutions condemning Assad's government for the violence.
With reporting by Reuters, AFP, AP, and Interfax