President Shimon Peres rejected speculation Israel might attack Iran to stop it making nuclear weapons and said US-led diplomacy was the solution.
The US favours negotiation to curb Iran's uranium enrichment, a process that can produce bombs, but such overtures have drawn scepticism in Israel, which sees a nuclear-armed Iran as a mortal threat. Iran denies having hostile designs.
The advent of Israel's right-wing Netanyahu government has redoubled international concern that Israel could go it alone with preventive strikes against Iran's nuclear sites, even at the cost of falling foul of the Obama administration.
But Mr Peres's office said he had told the visiting US envoy George Mitchell: "All the talk about a possible attack by Israel on Iran is not true. The solution in Iran is not military." Mr Peres lacks executive powers but is privy to policy-making. A spokesman for Prime Minister Benjamin Netanyahu declined to comment.