Russian President Vladimir Putin said he and U.S. President Barack Obama stuck to their positions over Syria but listened to each other during a one-on-one meeting on the sidelines of the G20 summit on Friday, and are looking for ways forward.

"He doesn't agree with me, I don't agree with him, but we listened to each other," Putin said of the "very constructive" 20-minute meeting, as the two-day economic summit, which was overshadowed by the crisis in Syria, concluded.

Relations between the two countries have become strained as the U.S. has pushed for military intervention in Syria's 2½-year-old civil war, while Moscow has stood by its long-time ally in the government of President Bashar al-Assad.

Putin blamed an alleged chemical attack last month on opponents of the Assad regime, saying it was a provocation, and suggested that a punitive U.S. military strike on the Middle Eastern country would harm the global economy and stifle growth.

Obama, in his own address to reporters shortly after, again held the Assad regime responsible for the Aug. 21 attack, and warned that failure to take action would embolden further use of chemical weapons by "rogue nations."

He said Russia and other countries ultimately will need to set aside their differences to work on a long-term political solution for Syria.

"I'm not itching for military action," Obama said.

Pressed by reporters, Obama declined to speculate whether he would go ahead with a strike if he is unable to win the support of Congress.

"I put it before Congress because I could not honestly claim that the threat posed by Assad's use of chemical weapons on innocent civilians and women and children posed an imminent, direct threat to the United States," he said. Obama said he will address the American people about the issue from the White House on Tuesday.

U.S. Senate Majority Leader Harry Reid formally introduced Obama's resolution on Friday. It would authorize "limited and specific" strikes on Syrian targets. A Senate vote is expected Wednesday, but final passage will require support from the House of Representatives, as well.

Obama said the leaders of the world's largest economies agreed that chemical weapons were used in Syria and that the international ban on chemical weapons needs to be maintained.

However, he said there was disagreement about whether force could be used in Syria without going through the United Nations. The United States has been unable to win UN Security Council approval for military action against Syria because of the opposition of veto-wielding Russia.  

"The majority of the room is comfortable with our conclusion that Assad, the Assad government, was responsible for their use," Obama said at a news conference, adding that this is disputed by Putin.

Canada condemns Syrian regime

Canada was one of 11 member states of the G20 which issued a statement at the close of the summit, condemning the Aug. 21 attack and calling for a strong international response, though it stopped short of insisting on military action.  

"The evidence clearly points to the Syrian government being responsible for the attack, which is part of a pattern of chemical weapons use by the regime," said the statement, which was signed by leaders and representatives of Australia, Canada, France, Italy, Japan, South Korea, Saudi Arabia, Spain, Turkey, Britain and the United States.  

"Those who perpetrated these crimes must be held accountable," it said.

Canada and other G20 countries on Friday also pledged further help to protect Syrian civilians from violence. Prime Minister Stephen Harper said in a statement that the government would contribute $45 million to organizations that provide food, clean water, sanitation, shelter and protection to civilians and to Syrians who have fled the country. Canada has contributed a total of $203.5 million since January 2012.

Separately, Putin said Russia will increase its own humanitarian aid to Syria and will continue helping the Assad regime even if it comes under attack.  

Putin answered with a firm "we will" when asked if Russia will keep providing assistance to Syria if it's attacked.  

He added that Russia has been supplying weapons to Syria and maintaining economic co-operation.  

Putin and his officials have previously said that Moscow has no intention of engaging in the conflict.  

However, Russia has increased its naval presence in the Mediterranean, which the Kremlin's chief of staff said could help Russia evacuate its citizens from Syria if necessary.

With files from Associated Press and CBC