Israeli military also said on Sunday that it imposed a curfew for residents of five Syrian towns in a demilitarised buffer zone of the Golan Heights.
“For your security you must stay at home and not go out until further notice,” Lieutenant Colonel Avichay Adraee, an Israeli army spokesman, said on X.
Since the rebel coalition, led by Islamist group Hayat Tahrir al-Sham, began its renewed offensive against government forces on Nov 27, Syrian government forces have left positions near the Israeli-held Golan, according to a war monitor.
Rami Abdel Rahman, head of the Syrian Observatory for Human Rights, said on Saturday that Syrian army forces had withdrawn from positions in Quneitra province, which includes part of the Golan Heights.
Most of the plateau has been occupied since 1967 by Israel, which later annexed it in a move not recognised by most of the international community.
In 1974, the buffer zone was established, separating the Israeli-held and Syrian territories, with UN peacekeepers stationed there since.
A UN Peacekeeping spokesperson said on Saturday that UNDOF personnel had observed “unidentified armed individuals in the area of separation, including approximately 20 who went into one of the mission’s positions in the northern part of the area of separation”.
The Israeli army said it was “assisting the UN forces in repelling the attack”.
The UN spokesperson said that “peacekeepers continue to carry out their mandated activities on the Golan”.
On Sunday, Lebanese media outlets reported an Israeli strike on Quneitra targeting an arms depot. The Israeli military declined to comment.
In a separate statement, the Israeli military said schools in the northern Golan Heights, in an area covering four Druze towns, would move to online teaching, also declaring a “closed military zone” in agricultural lands in the area.
Early in Syria’s war, which began in 2011 following the repression of anti-government protests, rebel forces and jihadist groups had taken over parts of Quneitra province.
In August 2014, Islamist rebels attacked UNDOF and took more than 40 Fijian peacekeepers hostage, holding them captive for almost two weeks.