Opposition leader Isaac Herzog spoke with French Foreign Minister Laurent Fabius on Friday ahead of the European official's upcoming visit to the region.
"Israel cannot feel safe or certain in face of agreements being reached with Iran," the Zionist Union chairman said in the phone call, according to a statement released by his office.
Herzog is currently in London on an official state visit.
It is vital for the State of Israel, he said, "and for the safety of the Western world that world powers negotiating with Iran won't compromise on important issues such as oversight" on Iran's uranium enrichment and nuclear plants.
He cautioned that a mistake in the negotiations means Israel – and the rest of the world – will pay a heavy price.
Herzog also denounced Friday's shooting attack in the West Bank, which claimed the life of 25-year-old Danny Gonen, and injured another 25-year-old, near the settlement of Dolev.