The United Nations last week estimated more than 1.9 million Syrians have fled the country since conflict began in early 2011. U.N. Secretary-General Ban Ki-moon said last month at least 100,000 people in Syria have died as a result of war.
The U.N. Security Council has been unable to adopt a formal resolution condemning the violence. Western allies are accused by their Russian counterparts of pushing language skewed toward rebel forces in draft resolutions.
Russian counts the Syrian government as a top military customer.
Ban told the Security Council in an open debate Monday he was frustrated by the divisions. He said the Security Council embraced its responsibility to protect civilian life in the 1990s.
"[Since] that time, divisions have too often stood in the way of action to meet urgent needs," he said in his address. "The tragedy in Syria is a particularly stark example."
The United Nations said it was working to respond to a massive influx of Syrian refugees streaming across the border into northern Iraq. Ban said the ongoing level of violence in Syria was intolerable.
"All parties to the conflict are systematically failing in their obligations under international humanitarian and human rights law to protect civilians," he said. "This must end immediately."