Syria: US presses Russia in bid to halt fighting
The US says it is working on plans to reduce the bloodshed in Syria and revive a nationwide ceasefire.
It says its "top priority" is to halt conflict in the city of Aleppo, where at least 200 people have died in a week of government raids and rebel shelling.
The US wants Russia to put pressure on the Syrian government to stop what it says is indiscriminate bombardment.
Russia says the strikes in Aleppo are targeting terrorists, but confirmed it was discussing a truce there.
Negotiations are under way to include Aleppo in a temporary "regime of calm", Lieut Gen Sergei Kuralenko, who heads Russia's ceasefire monitoring centre in Syria, told Russian media.
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The Russian and Syrian governments have said the Aleppo strikes are targeting the Nusra Front - a jihadist force that is not party to a ceasefire agreed in February.
But the US argues that such attacks are direct violations of the ceasefire, and accused the government of President Bashar al-Assad of targeting civilians.
On Saturday, more government strikes reportedly killed at least four people in rebel-held parts of Aleppo.
Mr Kerry is in Geneva to discuss the situation with the UN envoy to Syria, Staffan de Mistura, and the foreign ministers of Jordan and Saudi Arabia.
"The secretary made clear that ending the violence in Aleppo and returning ultimately to a durable, nationwide cessation is a top priority," state department spokesman spokesman John Kirby said.
Mr Kirby also called for an end to "regime obstruction of the delivery of humanitarian relief to all areas in need and to make concrete progress towards a political transition".
The truce between President Assad's forces and rebels in Syria has broken down in recent months, especially in the divided and besieged Aleppo.
Large parts of the city - Syria's largest - have been destroyed, leaving civilians without water and electricity for months.
A new round of UN-backed peace talks is set to start on 10 May in Geneva.