The top American envoy's appeal came as the second-round negotiations of the Geneva II international conference on Syria concluded without tangible results Saturday.
Lakhdar Brahimi, the UN-Arab League special envoy for Syria, said a proposed agenda for the next round of talks was agreed between delegates of the Syrian government and the opposition, but he did not reveal an exact date.
Kerry said this after the 2nd round of Geneva II talks on Syria failed
"There's no recess in the suffering of the Syrian people, and the parties and the international community must use the recess in the Geneva talks to determine how best to use this time and its resumption to find a political solution to this horrific civil war," Kerry said in a statement.
He blamed Syrian government's "obstruction" for slow progress in the talks, while praising the opposition for their "willingness to discuss all aspects of the conflict".
"We call on the regime's supporters to press the regime," Kerry said. "In the end, they will bear responsibility if the regime continues with its intransigence in the talks and its brutal tactics on the ground."
"We remain committed to the Geneva process and to all diplomatic efforts to find a political solution as the only way to a lasting and sustainable end to the conflict," he added.
In his meeting with King Abdullah II of Jordan Friday in Rancho Mirage, California, US President Barack Obama said: "We don't expect to solve this any time in the short term."
But he pledged to take "some immediate steps" to help the humanitarian situation in Syria and "some intermediate steps" to apply more pressure on the Syrian government.