"The Zionist (Israeli) regime is dying," said Ahmadinejad during a speech in northern Iran. "The criminals assume that by holding celebrations ... they can save the sinister Zionist regime from death and annihilation."
Ahmadinejad used an Arabic word, ismihlal, that can also be translated as destruction, death and collapse.
Iran doesn't recognize Israel, and Ahmadinejad has repeatedly called for Israel's destruction. Threatening exchanges between Iran and Israel have intensified since 2005, when Ahmadinejad said in a speech that Israel will one day be "wiped off the map." The Iranian leader has also described the Holocaust as a "myth."
"Nations of the region hate this criminal fabricated regime (Israel) and will uproot this fabricated regime if the smallest and shortest opportunity is given to them," Ahmadinejad said Wednesday in an address broadcast live on state television.
Israel considers Iran a serious threat because of its support for Hamas and Hezbollah militants, its nuclear program and its arsenal of long-range missiles, which can be fitted with nuclear warheads and are capable of striking the Jewish state.
Tehran is equipped with Shahab-3 missiles, which have a range of up to 1,250 miles. Israel is about 625 miles west of Iran.
Israel and the U.S. accuse Iran of using its nuclear program as a cover for a weapons program. Iran has denied the charges, saying its nuclear program is geared merely toward generating electricity, not bomb making.
"These are the words of a man who denies the Holocaust happened and is producing nuclear weapons while threatening Israel with extinction," Israeli Foreign Ministry spokesman Arye Mekel said.
"The international community has to take care of this problem to ensure that Iran never has nuclear weapons."
Israel is widely believed to have a large stockpile of nuclear weapons, but follows a policy it calls "nuclear ambiguity" and has never acknowledged or denied having a nuclear weapons program.
Iranian military officials have warned Israel in recent years that Iran would destroy Israel's Dimona nuclear reactor if the Jewish state were to attack Iranian nuclear facilities.