U.S. President Barack Obama cautioned Russian President Vladimir Putin Monday against his country's military intervention in Syria.

"I think Mr. Putin understands that ... with Afghanistan fresh in the memory, for him to simply get bogged down in an inconclusive and paralyzing civil conflict is not the outcome that he's looking for," the U.S. President told reporters in Paris, according to CNN.

Russia, an ally of embattled Syrian President Bashar al-Assad, started anti-ISIS airstrikes all over Syria on Sept. 30. Western countries. including the U.S., accused Russia of targeting Syrian opposition forces instead of Islamic State terror outfit.

Obama, in a closed-door meeting with Putin on Monday, expressed regret over the recent downing of a Russian fighter jet by the Turkish air force, a Kremlin spokesperson said, RT reported.

"President Obama expressed his regret for the recent loss of a Russian pilot and crew member and reiterated the United States' support for deescalation between Russia and Turkey," a White House official said, according to Press TV.

The downing of a Su-24M fighter jet by the Turkish air force on Nov. 24 has heightened tensions between the two countries. Turkey, a U.S. ally and NATO member country, continues to maintained that it's air force shot down the plane because it had violated Turkish airspace, as HNGN previously reported. Moscow dismissed Turkey's explanation, saying that the fighter jet was downed in Syrian airspace.