Kerry arrived in Paris on Friday pushing for a ceasefire in the city, home to retreating rebels backed by the United States which face an onslaught from Syrian forces supported by Russia.
US officials will meet their Russia counterparts in Geneva to try to "come to some kind of arrangement where we can see how civilians may be protected and what can happen with the armed opposition," Kerry said.
He did not sound upbeat about the chances of success, however, with Syrian President Bashar al-Assad and Russian President Vladimir Putin seemingly intent on pushing their advantage in Aleppo.
The rebels now control only a pocket of Syria's second city, whose fate is seen as pivotal to the outcome of a nearly six-year-old war that has killed more than 300,000 people.
"I know people are tired of these meetings, I'm tired of these meetings. People are sort of 'oh, another meeting'," he said from the US embassy in Paris.
"But what am I supposed to do? Go home and have a nice weekend in Massachusetts, while people are dying? Sit there in Washington and do nothing?" he added.
Foreign ministers from the Western and Middle Eastern backers of Syria's weakened opposition, including Kerry, will gather in Paris on Saturday for talks.