"We are not worried about Israel and its threats," Rafsanjani said when asked about the possibility of the Jewish state launching a pre-emptive strike against Iran's nuclear facilities.
"If Israel committed such an error, we would give it a slap it would never forget -- not only during several years but for all its history," said the powerful ex-president, who now heads Iran's top political arbitration body.
The interview, given to the Qatar-based Arab TV station Al-Jazeera, was also carried here on state television.
Iran has been accused by the United States and Israel of using an atomic energy programme as a cover for secretly developing nuclear arms, a charge Tehran angrily denies.
Last Friday, the International Atomic Energy Agency (IAEA) gave Iran until October 31 to clear up widespread suspicions that it is using an atomic energy programme as a cover for nuclear weapons development.
The resolution, passed by the IAEA's board of governors after intensive US lobbying, demands Iran answer all the IAEA's questions regarding its enrichment activities, provide unrestricted access to UN inspectors and a detailed list of its nuclear-related imports.
Rafsanjani dismissed warnings of severe consequences for Iran's foreign relations, especially with the European Union, if Tehran does not comply with IAEA demands.
Brussels has made the conclusion of a trade agreement with the Islamic republic conditional on Iran's acceptance of nuclear inspections.
"We are used to such threats and we are not afraid of them. We will do what we have to do and our scientists will continue their work," he said.