"I believe as we begin to get to Geneva... that it will become clear there is no political solution whatsoever if Assad is not discussing a transition and if he thinks he is going to be part of that future. It is not going to happen," Kerry claimed on Friday in a news conference following meetings with his Canadian and Mexican counterparts.
"We are also not out of options with respect to what we may be able to do to increase the pressure and further change the calculus," he added.
Kerry's remarks came as Syrian opposition groups vote on whether to participate in the UN-sponsored conference in Montreux, Switzerland.
Syria has been gripped by foreign-sponsored insurgency since 2011. According to reports, the Western powers and their regional allies - especially Qatar, Saudi Arabia, and Turkey - are supporting the armed militants operating inside Syria.
Meanwhile, the United Nations has also reported that more than four million other Syrians will be forced out of their homes in 2014 by the escalating conflict in the country that has killed more than 100,000 people.
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