In a telephone conversation late on Wednesday, the two presidents stressed that any use of military force against another country without a mandate from the United Nations is a blatant violation of international law.
Putin and Rouhani emphasized that the Syrian crisis must be resolved only through diplomatic means.
The remarks came shortly after the five permanent members of the UN Security Council held a closed-door meeting to discuss a British proposal for a draft resolution demanding a swift response to an alleged chemical weapon attack near Damascus on August 21, which killed hundreds.
Rouhani said Tehran strongly condemns any use of chemical weapons anywhere, but warned against jumping to a judgment before all aspects of the alleged attack have become clear.
The Iranian president expressed concern over reports that the West is preparing to launch a war against Syria and warned that any military intervention in the strategic Arab state could destabilize the whole Middle East.
Putin also refuted claims made by the US and its allies accusing the Syrian government of being behind the August 21 chemical attack. Moscow believes that the Syrian Army, which has the upper hand in the battle against foreign-backed militants, has no need to use chemical arms, he said.
The Russian leader said if the United States has evidence proving its claims that the Syrian government has used chemical weapons, it should share the intelligence with UN inspectors investigating the case.
Meanwhile, Commander of Iran’s Islamic Revolution Guards Corps (IRGC) Mohammad-Ali Jafari warned that the United States will face another Vietnam War if it attacks Syria.
The IRGC commander said Washington's new warmongering will cost the demolition of Israel.
Jafari’s remarks were echoed by Chief of Staff of Iran’s Armed Forces Major General Hassan Firouzabadi, who said any military action against Syria would burn Israel in flames.