Kerry, who is here for discussions with his Iranian counterpart to accelerate a deal on Tehran's controversial nuclear programme, voiced his backing for Russian efforts during his meeting with UN and Arab League envoy for Syria Staffan de Mistura.
"The United States is particularly concerned about the continued catastrophe that is unfolding in Syria where nearly three-quarters of the entire country are displaced people," Kerry said.
Russia, a key ally of Syrian President Bashar al-Assad, has been trying to re-start peace talks involving de Mistura. The plan involves meetings between representatives of the regime and the fractured opposition.
Russia is trying to arrive at a political solution bring together various interlocutors from Assad's government and opposition figures to stop the war.
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De Mistura, who is heading to Damascus next week, said that his focus is on Aleppo first because it is "an iconic example of where things could start sending the best signal."
"So we hope that the Russian efforts could be helpful, we hope that the UN efforts led by Special Envoy de Mistura can have an effect," he said.
More than 200,000 people have been killed in Syria since the beginning of the conflict in March 2011, according to rights groups.