The statement said that the cabinet had agreed that the Syrian government "has a track record of the use of chemical weapons and it is highly likely that the regime is responsible for Saturday's attack".
"While the full assessment of the strike is ongoing, we are confident of its success it was a limited, targeted and effective strike with clear boundaries that expressly sought to avoid escalation and did everything possible to prevent civilian casualties", May said.
"This is not about intervening in a civil war". It is not about regime change.
'The fact of this attack should surprise no-one.
During the special meeting, May and his ministers are expected to discuss a form of British participation in a potential military intervention led by France and the US.
"The Syrian regime has continued to use chemical weapons and will continue to do so".
Secretary-General António Guterres has also expressed his outrage at reports that civilians in the enclave are being targeted by toxic agents, saying that any confirmed use of chemical weapons, by any party to the conflict, "is abhorrent and a clear violation of global law".
Syria has firmly denied any links to the attack.
A spokesperson added the facility was "located some distance from any known concentrations of civilian habitation" and scientific analysis was used to "minimise any risks of contamination to the surrounding area".
The mission was only allowed after approval by MPs - they backed military action in Iraq in September 2014, and in Syria a year later, strictly limiting strikes to IS targets. And, I would simply say to the Prime Minister: "be very careful, because you do not have a majority in parliament".
Theresa May is prepared to take action against the Assad regime in Syria without first seeking parliamentary consent, sources have told the BBC.
A somber-looking May said she had not taken the decision lightly, but warned the response was necessary amid the growing threat to the West posed by the use of chemical weapons, which she said had been exposed by the Russian nerve-agent attack in Salisbury last month. Britain's Parliament is in recess until Monday, though it could be recalled for an emergency debate.
May does not legally require Parliament's backing for military action, though it is conventional for lawmakers to be given the chance to 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.
'And a significant body of information including intelligence indicates the Syrian regime is responsible for this latest attack.
"Bombing can not substitute for diplomacy", he said.
May recalled the ministers from their Easter holiday for the meeting at 3.30 pm (1430 GMT) in Downing Street to discuss Britain's response to what she has cast as a barbaric attack that can not go unchallenged.