JERUSALEM — Israel’s defense minister became the first ally in Prime Minister Benjamin Netanyahu’s coalition to break ranks on Saturday as he called for an immediate halt to the far-right government’s contentious plan to overhaul the country’s judiciary.

In a televised address, Israeli Defense Minister Yoav Gallant expressed concern over the turmoil within Israel’s military that he said posed a threat to the country’s security. Citing the need for dialogue with the opposition, Gallant asked that Netanyahu’s coalition wait until after Parliament reconvenes from its holiday break next month before pushing ahead with its divisive plan to weaken the Supreme Court.

“For the sake of Israel’s security, for the sake of our sons and daughters, the legislative process must be stopped at this time,” Gallant, a top official in Netanyahu’s Likud party, said.

The government’s plan to increase its control over the judiciary has sparked the largest protest movement in Israeli history and triggered a grave national crisis, including even warnings from the president of civil war. Critics say the law is tailor-made for Mr. Netanyahu and encourages corruption.

On Saturday, tens of thousands of protesters took to the streets as they have every week since the start of the year — in many cases bringing parts of Jerusalem and Tel Aviv to a standstill. It has also raised the hackles of Israel’s closest allies, testing its ties with the United States.

In spite of the backlash, Netanyahu has dismissed offers for a compromise, including from Israel’s mainly ceremonial president earlier this month.

Supporters of the judicial overhaul underway in Israel say it will restore power to elected legislators and make the courts less interventionist. Critics say the move upends Israel’s system of checks and balances and pushes it toward autocracy.