Prime Minister Theresa May held an emergency cabinet to discuss joining mooted strikes by the US and allies, with ministers agreeing "on the need to take action", her Downing Street office said in a statement.
May's office added that she and her top team "agreed the prime minister should continue to work with allies in the United States and France to coordinate an international response".
US President Donald Trump is considering his military options in Syria after Saturday's alleged chemical attack against the rebel-held town of Douma.
His French counterpart Emmanuel Macron said he was in daily contact with Trump, stating France has evidence that the regime of Syrian President Bashar al-Assad was behind the attack.
But British involvement in further military intervention is controversial at home, in a country still haunted by its role in the US-led invasion of Iraq.
The government said it is "highly likely" that Assad is responsible for the Douma attack, with ministers agreeing "it was vital that the use of chemical weapons did not go unchallenged".
But rival politicians and some Conservative colleagues have called for a parliamentary vote before any British involvement.
Opposition Labour leader Jeremy Corbyn said it is "vital that parliament has the chance to debate and decide in advance" of any military action, which he warned "risks a dangerous escalation of the conflict".
French President Emmanuel Macron has said that his country has proof the Syrian government was behind the chemical attack. Source: AAP
Corbyn has also evoked memories of the Iraq War, when lawmakers approved joining in the face of strong public opposition.
A YouGov poll in The Times conducted this week found that 43 percent of voters oppose strikes in Syria, with 34 percent unsure and only 22 percent supportive.
Calls for parliament vote
Formally, the prime minister has the right to go to war without approval from parliament, but a convention has been established in previous conflicts where MPs have a vote either before or shortly after military action begins.
A separate YouGov survey on Thursday found 61 percent of people think it would be necessary for parliament to vote on military action against Syria, with just 18 percent saying it was not necessary and 21 percent undecided.
British lawmakers voted down taking military against Damascus in 2013, in what was widely viewed as an assertion of parliamentary sovereignty on the use of force.
Political satirist Kaya Mar holds his painting of British Prime Minister Theresa May outside Downing Street. Source: AAP
But they backed action in Iraq the following year, and again in Syria in 2015, strictly limiting strikes to Islamic State (IS) group targets.
Britain continues to support the US-led coalition targeting IS jihadists in Iraq and Syria, and has conducted more than 1,700 strikes.
Opposition Liberal Democrat leader Vince Cable told the BBC that parliament "can and should be recalled immediately" to hold a vote on the latest possible action.
"The position is a very dangerous one because of Russian involvement, also because we have an erratic president of the United States."
Anti-conflict coalition Stop the War called on Britons to lobby their lawmakers to prevent an "escalation of the war" and planned a Friday protest outside Downing Street.
Some MPs have backed Britain acting against Syria, warning that the use of chemical weapons was in breach of international law and could not be allowed to go unpunished.
Conservative former London mayoral candidate Zac Goldsmith, tweeted: "We need a clear response to the Syrian chemical outrage".
Other members of May's Conservative party have urged restraint in a highly fraught situation.
"What we've got here in Syria is a choice between monsters on the one hand and maniacs on the other," Julian Lewis, the chairman of the House of Commons defence committee, told the BBC.
