The Syrian government has denied any suggestion that it was involved in yesterday's car bombings in Damascus which left more than 40 people dead.
The UN Security Council "condemned in the strongest terms the terrorist attacks" after intense talks between the 15 members.
European and US officials want the UNSC to impose an arms embargo and other sanctions on Syria's government because of its nine-month-old crackdown, which UN officials say has killed more than 5,000 people.
But Russia, an old ally of Damascus, wants any resolution to be even-handed.
"If the requirement is that we drop all reference to violence coming from extreme opposition, that's not going to happen," UN ambassador Vitaly Churkin said in New York after Russia submitted a revised draft resolution to the council.
"If they expect us to have arms embargo, that's not going to happen," he said. "We know what arms embargo means these days. It means that - we saw it in Libya - that you cannot supply weapons to the government but everybody else can supply weapons to various opposition groups."
Germany's UN ambassador Peter Wittig said European countries wanted to see more weight behind the Arab League, which has ordered sanctions against Syria.
He said there had to be "demands to release political prisoners" and "a clear signal for accountability for those who have perpetrated human rights violations."
Russia and China vetoed a European-drafted resolution in October which condemned the government violence and threatened possible sanctions.
President Bashar al-Assad's government blamed al-Qaeda for the suicide attacks on two Damascus bases. But the Syrian opposition say Mr Assad's forces committed the strikes and the Security Council statement pointedly left out offering traditional condolences to the government.
Council members expressed "sincere condolences to the victims of these heinous acts and to their families, and to the people of Syria." The council's standard statement for terrorist attacks normally offers sympathy to the government.
UN leader Ban Ki-moon says he is "gravely concerned" at the escalating violence, but also stresses that Mr Assad must fully implement an Arab League peace plan to end 10 months of strife in the country which the UN says has left at least 5,000 dead.
Mr Ban kept up calls for "credible, inclusive and legitimate" political change in Syria, said his spokesman Martin Nesirky, adding that the government must "fully and speedily" implement the Arab League peace plan.
Western diplomats have expressed scepticism that Arab League monitors in Damascus will be allowed to work effectively and Mr Ban said the full mission "must be given unhindered access."
