As of now, the Syrian army and fighters from Lebanese Shiite movement Hezbollah advanced on the nearby villages.
The jihadist Al-Nusra Front and Syrian militants seized Kasab, an Armenian town, in March.
It is a strategically important city because it is located near the only border crossing with Turkey in Latakia province.
Syria has been torn by civil war for three years, with the West calling for Assad to step down.
Moscow condemned the rise of terrorism in Syria.
The Kremlin believes the international community can take steps toward a peaceful settlement of the conflict, rather than force regime change on Damascus.
More than 150,000 people have been killed since the start of the civil war in spring 2011, a third of them civilians, according to Syrian Observatory for Human Rights’ April data. Over two million Syrian refugees have fled for Europe, North Africa and other regions, according to the United Nations Refugee Agency.