Israel's security cabinet is united in its opposition to the framework deal reached between world powers and Iran, The Jerusalem Post quoted Israeli Prime Minister Benjamin Netanyahu's office as saying on Friday.
Netanyahu, who earlier spoke by phone with US President Barack Obama, said that he was "vehemently opposed" to the agreement.
Obama called Netanyahu within hours of the deal being struck, saying it represented significant progress toward a lasting solution that cuts off Iran's path to a nuclear weapon.
But Netanyahu said in a statement after the conversation that a deal based on the framework announced in Lausanne, Switzerland "would threaten the survival of Israel."
"This deal would legitimize Iran's nuclear program, bolster Iran's economy and increase Iran's aggression and terror throughout the Middle East and beyond," Netanyahu said.
"It would increase the risks of nuclear proliferation in the region and the risks of a horrific war."
Israel said in the past that it would consider taking a unilateral action to prevent Iran from developing a nuclear weapon, a warning taken to mean that it could launch air strikes against Iran's nuclear facilities.