Kremlin aide Yury Ushakov told reporters Putin would be holding "many bilateral meetings" at the two-day summit, which starts on Sunday in Antalya, Turkey, but an encounter with Obama was not on the agenda.
"A meeting between Vladimir Putin and Barack Obama is not officially planned," Ushakov said.
"But we cannot exclude the possibility that the presidents will interact within the summit's framework."
Moscow's relations with Washington slumped to a post-Cold War nadir over Russia's annexation of Crimea from Ukraine in March 2014 and its subsequent support of an insurgency in the country's east.
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Putin is expected to discuss the Syria crisis in bilateral encounters with German Chancellor Angela Merkel, British Prime Minister David Cameron, King Salman of Saudi Arabia and Turkish President Recep Tayyip Ergodan, Ushakov said.
International powers are engaged in a diplomatic push to resolve the nearly five-year conflict, in which around a quarter of a million people have died.
Around 20 countries and international bodies will meet in Vienna tomorrow to try to push forward a peace plan that would include a ceasefire between the regime and some opposition groups, and talks to find a political solution
Putin is also expected to meet Italian Prime Minister Matteo Renzi International Monetary Fund (IMF) chief Christine Lagarde on the margins of the G20.