They crossed in a UN convoy in the afternoon into the Israeli-occupied sector, an AFP correspondent said.UN peacekeepers in Golan
The peacekeepers in the Golan Heights withdrew to the Israeli-occupied side after the foreign-backed militants advanced near their positions, a UN spokesman said.
The armed groups posed "a direct threat to the safety and security" of the UN Disengagement Observer Force (UNDOF) troops, spokesman Stephane Dujarric said.
UNDOF monitors a 1974 ceasefire between the Zionist entity and Syria on the Golan Heights.
In late August, insurgents on the Syrian side including Al-Qaeda affiliate Al-Nusra Front seized the Quneitra crossing and kidnapped more than 40 Fijian UNDOF troops, before they were released two weeks later.
They also clashed with 75 Filipino members of the force, who eventually fled a nearby outpost.
Dujarric said the situation on the Syrian side of the Golan "has deteriorated severely" and that "armed groups have made advances in the area of UNDOF positions".
The fighting has driven thousands of Syrian families from their homes.
"Clashes between government forces and the armed opposition have intensified in recent days in Quneitra governorate -- in Quneitra city in particular, where access to clean water, food, and health care is limited," the International Committee of the Red Cross said in a statement.
The ICRC said it has provided emergency relief for more than 50,000 people, but warned the number of displaced people was "expected to grow".