"We took a very measured step last night. We are prepared to do more. We hope that it will not be necessary," Ambassador Nikki Haley told the Security Council.
Friday's session saw U.S. and its allies exchange blame with Russia and Bolivia -- which called the meeting -- and ended without a vote on a draft resolution to condemn the chemical weapons attack in Khan Shaykhun, Idlib.
The attack on Tuesday killed at least 100 people and injured 500.
In response, the U.S. fired 59 Tomahawk missiles at a Syrian military air base American officials believe was used to carry out the attack, the Pentagon confirmed.