Prime Minister Benjamin Netanyahu, who says his aim is to balance out branches of government, wields a parliamentary majority along with his religious-nationalist coalition allies but his planned judicial overhaul has sparked concern at home and abroad.
As the changes head toward ratification, the protests have escalated, affecting the economy - the shekel has slipped - and extending to a threat by some military reservists not to heed call-up orders.
President Isaac Herzog has appealed for the overhaul to be postponed and presented an alternative plan to the changes on Wednesday which was swiftly rejected by the prime minister.
"I came with my friends here to Tel Aviv, to demonstrate against what is called reforms," Ronen Shaike, 47, told Reuters at a demonnstration in the city, saying he wanted to defend the country's democracy, which he accused the government of seeking to destroy.
Netanyahu, who returned to office for a sixth term in late December, has said the demonstrations are aimed at toppling him. He is on trial in three corruption cases and denies all wrongdoing.
"I'm here to demonstrate with the people of Israel, against the revolution, against the changing of our state," said Dalia Yosef, 72, also at the Tel Aviv demonstration.
(Reporting by Emily Rose; Editing by Frances Kerry)