Thousands of people are said to have gathered in central Tel Aviv. The police used water cannons loaded with foul-smelling liquid to disperse the demonstrators, who had lit fires and blocked a motorway.
Among those forced away by the police were, according to Haaretz, Einav and Natalie Zangauker, whose son and brother Matan is being held hostage in Gaza.
Several thousand more demonstrated outside Prime Minister Benjamin Netanyahu's home in Jerusalem. There, too, the police are said to have dispersed the demonstrators with violence.
According to Israeli media, the demonstrators are protesting against Netanyahu's increasingly authoritarian leadership.
"This is not about Gallant," writes Haaretz's deputy editor-in-chief Noa Landau on X.
"This is about Netanyahu getting rid of the last person in his cabinet who dared to challenge him, and replacing him with a puppet."
Israel Katz, former Foreign Minister, replaces Gallant as Defense Minister.
