Dozens of Jewish youths gathered Tuesday evening near the Ayelet Hashahar Synagogue at Givat Ze'ev, north of Jerusalem.
There are reports that bulldozers are on their way.
The police asked the High Court for another postponement of the demolition, but the court rejected this request.
The Ayelet Hashahar synagogue, which has been in use for over 20 years, was slated to be demolished after far-left group Yesh Din filed a petition with the High Court, claiming the structure had been build on privately-owned Palestinian land.
A petition to demolish it has been working its way through the courts for at least three years.
Members of the congregation have offered the land's alleged owners a high price for the purchase or rental of the land, but the owners, and their lawyers, have insisted that the synagogue be torn down.