"We have to negotiate in the end. We've always been willing to negotiate in the context of the Geneva I process," the US top diplomat said, referring to the June 30, 2012 conference on Syria.
The US diplomat added that Washington "reignited" efforts to find a political solution to end the civil war in Syria.
"What we're pushing for is to get him [Syrian President Bashar Assad] to come and do that, and it may require that there be increased pressure on him of various kinds in order to do that," Kerry said.
Both UN-backed Geneva I and Geneva II conferences ended in an impasse between Syrian President Bashar Assad and the country's splintered opposition.
At Geneva II last January, Kerry echoed US President Barack Obama's statement made three years earlier that "time has come for President Assad to step aside."
The United States, along with a number of allied countries, have maintained and expanded a sanctions regime against Syria's economy and individual officials for over a decade.
