(JTA) — Thousands of Haredi Orthodox Jews protested in Jerusalem against plans to enlist men from their community into the military.

The men gathered on Thursday night near the city’s military draft bureau and heard rabbis warn that army service would irreparably harm their way of life.

Reuters quoted Rabbi David Zycherman as saying: “The government wants to uproot and secularize us, they call it a melting pot, but people cannot be melted.”

Prime Minister Benjamin Netanyahu’s coalition government has committed to expanding the draft of ultra-Orthodox men, most of whom receive exemptions on religious grounds, in order to reduce pressure on the middle classes.

The party of Finance Minister Yair Lapid, Netanyahu’s main coalition partner, received wide support at the polls in January on a pledge to resist demands by religious parties and to spread the load of army service and taxation more evenly.

Police spokesman Micky Rosenfeld said at least 20,000 protesters took part. He said there were about a dozen arrests after protesters hurled bottles and stones at officers, some on horseback, who used stun grenades to quell the unrest.

A water cannon was also deployed as protesters set alight garbage bin. At least six officers required medical treatment and two were taken to hospital, Rosenfeld said.

Most Israeli men and women are called up for military service for up to three years when they turn 18. Exceptions are made for most Arab citizens of Israel, as well as ultra-Orthodox men and women.