The Russian foreign minister wore a mask which had been given to him by pool reporters for his birthday.
Some 38 percent of Russians said he was the top politician, but this figure was down on previous years.
Sergei Lavrov accused Obama of putting personal issues before those of the state and undermining ties between Washington and Moscow.
Idlib is the last significant rebel-held area in Syria, and since December has come under a renewed offensive by regime troops supported by their Russian and Iranian allies.
Sergey Lavrov accused Washington and its allies of trying to establish a new world order "based on rules they created themselves."
Dmitry Peskov said the visit of Foreign Minister Sergei Lavrov to the White House last week is not necessarily a sign of thawing relations between the two countries.
The U.S. is set to deploy some 600 soldiers to guard eastern Syria's oil fields against Islamic State remnants, though Trump has said he wants to bring in a U.S. company to develop the resources.
President Donald Trump withdrew U.S. forces from Kurdish-held areas of Syria this week, leaving them open to a new Turkish offensive.
Foreign Minister Sergei Lavrov also warned that proposed NATO expansion poses a threat to peace in Europe.
"Other tools have somehow disappeared from U.S. diplomacy's arsenal," Russian Foreign Minister Sergei Lavrov said.
Russia's top diplomat described the NATO alliance as a bully working to spread its influence across the Balkans.
Foreign Minister Sergey Lavrov decried "attempts at imposing foreign models of development and values on the people of the Middle East."
The two countries have been locked in a territorial dispute over a remote island chain since the end of the conflict.
Israel purportedly rejected a previous plan that would have seen Iranian forces kept about 60 miles from its border.
Russia's Sergei Lavrov has accepted the invitation of North Korea's foreign minister.
In a long interview with state media, Lavrov seemed to reiterate comments made by Kremlin aide Yury Ushakov, who said Trump invited Putin to Washington.
Foreign Minister Sergei Lavrov said Moscow warned the Americans of its "red lines."
Moscow's top diplomat accused the West of targeting the Russian public, not elites, with sanctions.
Russia doubts claims that the U.S. will not play a role in operating and controlling the system in Japan.
As forces supported by the U.S. and Russia defeat ISIS across Syria, Secretary of State Rex Tillerson seeks Moscow's help to prevent a new conflict.
Russia's foreign minister said Moscow currently regarded Washington with "anticipation."
The top foreign affairs university in Moscow marked Diplomats' Day with a song.
"The ball is in their court," said the country's Deputy Foreign Minister Vladimir Titov.
Russia's top diplomat said the Kremlin wants a relationship of "equality" with the U.S.