Israel's president warned on Sunday that the country faced a constitutional crisis over a contested plan to rein in the judiciary, and said he was mediating between parties, Reuters reported.

Prime Minister Benjamin Netanyahu, now in his sixth term, wants to put controls on the Supreme Court, which members of his religious-nationalist coalition accuse of overreach and elitism.

Opponents, who held nationwide protests on Saturday, say it would cripple judicial independence, foster corruption, set back minority rights and deprive Israel's courts of credibility that helps fend off war-crimes charges abroad.

"We are in the grips of a profound disagreement that is tearing our nation apart. This conflict worries me deeply, as it worries many across Israel and the [Jewish] Diaspora," President Isaac Herzog said in a statement.

"I am now focused on ... two critical roles that I believe I bear as president at this hour: averting a historic constitutional crisis and stopping the continued rift within our nation," he added. 

In televised remarks at his weekly cabinet meeting, Netanyahu made no mention of Herzog's overture.

Judicial reforms, he said, had been sought by previous governments of various political stripes "and no one then thought about talking about an end to democracy."