U.N. inspections have proved the regime of President Bashar Assad used the weapons on insurgent areas near Damascus last month, he said.
"The Security Council must be prepared to act next week," Kerry said. "It is vital for the international community to stand up and speak out in the strongest possible terms about the importance of enforceable action to rid the world of Syria's chemical weapons.
"So I would say to the community of nations, time is short," he added. "Let's not spend time debating what we already know. Instead, we have to recognize that the world is watching to see whether we can avert military action and achieve through peaceful means even more than what those military strikes promised."
Kerry said the complete removal of Syria's chemical weapons was possible through peaceful means, but "that will be determined by the resolve of the United Nations to follow through on the agreement that Russia and the United States reached in Geneva, an agreement that clearly said this must be enforceable, it must be done as soon as possible, it must be real."
"It is important that we accomplish the goal in New York [at the United Nations] and accomplish it as rapidly as possible," he said.
Washington reportedly will give up on including an armed threat in a U.N. motion on Syria's chemical arms while Moscow will show evidence rebels used nerve gas.
The United States, Britain and France are ready to back down from their demand in the hope of smoothing the path to adoption of a Security Council resolution calling for Syria's chemical weapons to be dismantled and destroyed, The Independent reported Thursday.
With the change of position, the resolution could be adopted as early as this weekend, the British newspaper said.
The Obama administration had no immediate comment on the report.
State Department spokeswoman Marie Harf repeated the administration's position Wednesday it would "maintain the threat of military force" independent of the U.N. process if Syria fails to meet its commitments.
A top diplomat at the United Nations told The Independent he was "optimistic" Syrian ally Russia, with China's support, would back the disarmament resolution ahead of Monday's start of the annual U.N. General Assembly session, attended by leaders of most of the world's nations.
The resolution is based on a framework agreement reached Saturday between Washington and Moscow, giving the Security Council authority to review Syria's compliance with the Chemical Weapons Convention, which Syria agreed to join as the U.S.-Russian framework was finalized.
Under the framework deal, the Assad regime is expected to submit a "comprehensive listing" of all its chemical weapons supplies and facilities by the end of this week.
Harf told reporters at the State Department Wednesday the weekend time frame is not a hard-and-fast deadline.
"Our goal is to see forward momentum, and obviously we know it takes time as well," she said. "This is really the first step in assessing how serious the Syrian regime is at working toward this framework that we and the Russians have agreed to."
All Syria's chemical weapons are supposed to be destroyed by June 30, 2014.