Tensions have soared over the possible military escalation, with President Donald Trump warning Russia that “missiles will be coming” in response to an alleged chemical attack in Syria.
“What the Syrian people want and need is peace and justice, not further military escalations or impunity,” Sweden's UN ambassador Olof Skoog told reporters.
“Let that also be a response to planned military interventions. Whatever happens now needs to be in line with international law.”
Sweden is a non-permament member of the Security Council, which on Tuesday failed to agree on setting up an investigation of chemical weapons use in Syria, with Russia and the United States failing to win support for their rival proposals.
Skoog said that while the council failed to agree on a way forward, the inaction did not create a “legal vacuum” that would justify air strikes by the United States, France and Britain.
“Whatever happens next, there is international law and it needs to be abided on,” said the Swedish ambassador.
Swedish tabloid Aftonbladet reported that Foreign Minister Margot Wallström was locked in crisis talks discussing the conflict with colleagues and advisers.
The warning set the stage for a new clash at the Security Council over the legality of any military action, which is likely to be carried out without a UN mandate.
Sweden is a member of the European Union along with Britain and France, but is not part of Nato.
Russia has repeatedly warned at the council that Western military action in Syria would be illegal and could lead to a wider conflict.
After the three failed votes at the council on Tuesday, Russian Ambassador Vassily Nebenzia implored the United States to change course.
“I would once again ask you, once again beseech you to refrain from the plans that you are currently developing for Syria,” he said.