The Syrian authorities will face up to armed groups firing indiscriminately on demonstrators and the forces of order, the interior ministry said in a statement.
Mass protests calling for sweeping changes in Syria's authoritarian regime have turned deadly, with the government and protesters both claiming heavy casualties as the country's three-week uprising entered a dangerous new phase.
"We will not allow confusion between peaceful demonstrations and (acts of) sabotage (aimed at) sowing discord, harming national unity and destabilising the foundations of Syrian policy," said the statement published by the official SANA news agency.
"To preserve the security of the country, citizens and public institutions, the Syrian authorities will face up to these plotters and those behind them, under the law limiting the use of arms," it said.
The statement spoke of "plotters ... pushed by known foreign parties who reject the reforms and turn up their noses at the popular demands".
The bloodiest clashes occurred in the restive city of Daraa on Friday, where human rights activists and witnesses said Syrian security forces opened fire on tens of thousands of protesters, killing 25 people and wounding hundreds.
At the same time, state-run TV said 19 policemen and members of the security forces were killed when gunmen opened fire on them.
It was the first significant claim of casualties by the Syrian government, which has contended that armed gangs rather than true reform-seekers are behind the unrest - and it could signal plans for a stepped-up retaliation.
The protests were in response to calls by organisers to take to the streets every Friday to demand change in one of the most rigid nations in the Middle East.
Marches were held in cities across the country as the movement showed no sign of letting up, despite the violent crackdowns.
At least 32 protesters were killed nationwide, according to human rights activists. The bloodshed lifted the death toll from three weeks of protests to more than 170 people, according to Amnesty International.
US President Barack Obama in a statement on Friday night condemned the violence and called on Syrian authorities to refrain from attacks on peaceful protesters.
"Furthermore, the arbitrary arrests, detention, and torture of prisoners that has been reported must end now, and the free flow of information must be permitted so that there can be independent verification of events on the ground," he said.
The calls for reform have shaken the regime of President Bashar Assad, whose family has ruled Syria for more than 40 years.
Assad, a British-trained eye doctor, inherited power from his father 11 years ago and tried to help the country emerge from years of international isolation and lift Soviet-style economic restrictions.
But despite early promises of social and political change, Assad has slipped back into the autocratic ways of his father.
As the wave of protests have gathered steam, Assad has offered some limited concessions - firing local officials and forming committees to look into replacing the country's despised emergency laws, which allow the regime to arrest people without charge. On Thursday, he granted citizenship to thousands of Kurds, fulfilling a decades-old demand of the country's long-ostracised minority.
But those gestures have failed to mollify a growing movement that is raising the ceiling on its demands for concrete reforms and free elections.
Daraa has largely been sealed off and phone calls go through only sporadically.
But residents said by phone that mosques were turned into makeshift hospitals to help tend to hundreds of wounded.
One man who helped ferry the dead and wounded to the city's hospital said he counted at least 13 corpses.
"My clothes are soaked with blood," he said by phone from Daraa. Like most activists and witnesses, he requested anonymity for fear of reprisals.
A nurse at the hospital said they had run out of beds; many people were being treated on the floor or in nearby mosques.
Videos posted on YouTube showed demonstrations in at least 15 towns, large and small, across the country.
Ammar Qurabi, who heads Syria's National Organization for Human Rights, said 32 people were killed nationwide: 25 in Daraa, three in the central city of Homs, three in the Damascus suburb of Harasta and one in the suburb of Douma.
A city of about 300,000 near the border with Jordan, Daraa is suffering sustained economic effects from a years-long drought.
