Peter Wittig said the 15-member council "did not live up to its responsibilities" in face of Russian opposition to a European-drafted resolution that would have threatened Damascus with "targeted measures."
"I think it was a decision taken in Moscow. It was a very deliberate decision" to back the regime of President Bashar al-Assad, Wittig said at an event in Washington.
The German envoy strongly criticized Russia for linking the debate on Syria to the NATO attacks in Libya. Moscow argues that NATO and its partners overstepped an UN resolution passed in March last year that authorized military force to stop ousted Libyan strongman Muammar Qaddafi assault on civilians.
"I sometimes have a feeling it is a pretext for not engaging in a more constructive manner on Syria," Wittig told an audience at the Woodrow Wilson Center. "I don't think the cases can be compared."
Wittig deplored the ongoing violence in Syria, denouncing the "ruthless repression of the freedom movement." The situation in Syria "was and still is of utmost concern," he said.
According to the UN, 5,400 people have been killed since protests erupted in March. The UN Security Council is struggling to agree a common position on Damascus's crackdown on the dissent.
Russia and China vetoed a European-drafted resolution on Syria in October.
Russia has since proposed its own resolution, which condemns the government and opposition violence, but Western council members have rejected it as too weak.