Syria's new rebel-led government said 14 interior ministry officials were killed and 10 wounded in an “ambush” by forces loyal to ousted President Bashar al-Assad in the west of the country.
They say the battle took place near the Mediterranean port of Tartus on Tuesday.
Reports said security forces were ambushed while trying to arrest a former officer in connection with his role in the notorious Saidnaya prison, near the capital Damascus.
Just over two weeks ago, Assad's presidency fell to rebel forces led by the Islamist faction Hayat Tahrir al-Sham (HTS).
The UK-based Syrian Observatory for Human Rights (SOHR) said three militants were also killed in the clashes.
SOHR added that security forces later brought in reinforcements.
In a separate development, Syrian authorities imposed a curfew in the central city of Homs, state media said.
Reports say it followed riots after a video purported to show an attack on an Alawite shrine.
Syria's interior ministry said it was an old video dating back to the rebel offensive on Aleppo in late November, and the violence was carried out by unknown groups.
SOHR reported that one demonstrator was killed and five wounded in Homs.
Demonstrations were also reported in areas including the cities of Tartus and Latakia and Assad's hometown of Kardaha.
The Alawites are the minority sect from which the Assad family descends and to which many of the former regime's political and military elite belong.
The HTS-led blitzkrieg, which began in northeastern Syria and spread across the country, ended more than 50 years of rule by the Assad family.
Assad and his family were forced to flee to Russia.
HTS has since pledged to protect the rights and freedoms of many religious and ethnic minorities in Syria.
HTS is designated as a terrorist organization by the UN, USA, EU, UK, etc.
Protests broke out across the country on Tuesday over the lighting of the Christmas treewhich prompted new calls for the new authorities to protect minorities.