During a visit to Vladivostok on August 31, Putin said it would be "utter nonsense" for the Syrian government to use chemical weapons when its forces are winning in the fight against rebels.
Putin's comments come as the United States considers a possible military operation against the Syrian government over the alleged poison-gas attack.
A U.S. intelligence report said U.S. officials had "high confidence" the Syrian regime carried out the August 21 attack, which the report says killed 1,429 people.
U.S. President Barack Obama said on August 30 he had not made a final decision about an attack.
Obama said Washington was considering the possibility of what he called a "limited, narrow" military operation to send the message that chemical weapons should not be used.
"The world has an obligation to make sure that we maintain the norm against the use of chemical weapons," Obama said. "Now, I have not made a final decision about various actions that might be taken to help enforce that norm."
The Syrian government has condemned the U.S. report as "fabricated" and based on "lies" put forward by rebels.
The Syrian government has denied involvement in any chemical attack, instead accusing rebels of being behind such attacks in a bid to trigger Western intervention and reverse battlefield losses.
Putin said Obama, a Nobel Peace Prize laureate, should consider potential victims of a military strike.
Russia, a longtime ally and arms supplier to the Syrian government, has said any use of military force without UN approval would be a breach on international law.
Russia has blocked efforts in the UN Security Council to agree on a resolution that would authorize foreign strikes in Syria.
Putin said plans to deliver strikes against Syria have been prompted by recent Syrian government's advances against rebels.
He said the British Parliament's decision not to sanction participation in military strikes was unexpected, and showed "there are people of common sense there."
A Russian Foreign Ministry statement on August 30 called for Washington to await the results of a United Nations investigation into the alleged attack.
Earlier on August 31, United Nations inspectors who have been probing the alleged chemical-weapons attack near Damascus left Syria, crossing into Lebanon after carrying out four days of inspections.
The samples they collected will now be analyzed in laboratories around the world. The United Nations has not said when the inspectors' final report might be released.
The lack of a Security Council resolution has limited the number of countries that have publicly said they would back a U.S.-led military operation.
Only France has publicly indicated it is ready to join any U.S. attack. Britain said it would not be involved after lawmakers voted down a motion on August 29.
In Turkey, Prime Minister Recep Tayyip Erdogan said any international military intervention should be aimed at bringing an end to the rule of Syrian President Bashar al-Assad.
Erdogan said the point of any military action should be to stop the bloodshed and weaken the regime "to the point where it gives up." He said an operation of one or two days "will not be enough."
Erdogan cited the NATO operation against Serbia during the 1999 Kosovo war as an example. That war ultimately led to a change in government in Belgrade.