Israel's existence is an "insult to all humanity," Iran's president said Friday in one of his sharpest attacks yet against the Jewish state, as Israel openly debates whether to attack Iran over its nuclear program.

Mahmoud Ahmadinejad said confronting Israel is an effort to "protect the dignity of all human beings."

"The existence of the Zionist regime is an insult to all humanity," Ahmadinejad said. He was addressing worshippers at Tehran University after nationwide pro-Palestinian rallies, an annual event marking Quds (Jerusalem) Day on the last Friday of the holy month of Ramadan.

The comments are "reminiscent" of a letter written about the Jews and signed by Adolf Hitler in 1919, Rabbi Marvin Hier, Founder and Dean of the Simon Wisenthal Center, says.

"Even though Ahmadinejad is attacking the state of Israel, we know what he means," Rabbi Hier said.

Israel considers Iran an existential threat because of its nuclear and missile programs, support for radical anti-Israel groups on its borders and repeated references by Iranian leaders to Israel's destruction.

Ahmadinejad himself has repeatedly made such calls, as has Iran's Supreme Leader Ayatollah Ali Khamenei.

Rabbi Hier compares Ahmadinejad's comments to the notion found in Hitler’s letter referencing the "removal of Jews all together." "Twenty-two years later he implemented everything, and the same is true about Ahmadinejad," Rabbi Hier said.

"We assume it's only rhetoric, but we once paid a very high price for assuming Hitler was talking rhetoric," he said.

The leader of the Lebanese Shiite militant Hezbollah, which has ties to Iran, says his group will transform the lives of millions of Israelis to "hell" if Israel attacks Lebanon.

Sheikh Hassan Nasrallah says the group has a list of Israeli targets that it can hit with few rockets.

"We can transform the lives of millions of Zionists in occupied Palestine to a real hell," he said.

Israel and Hezbollah fought a deadly, inconclusive monthlong war in 2006, when Hezbollah fired about 4,000 rockets at Israel.

Iran has denied allegations that it is seeking to build nuclear weapons, saying its nuclear program is peaceful and aimed at producing electricity and radioisotopes used to treat cancer patients.

Israel has been carrying on an increasingly public debate about whether to attack Iran's nuclear facilities. Israel's official position is to favor diplomatic and economic measures to persuade Iran to halt its uranium enrichment program, but Israel insists that Iran must not be allowed to obtain nuclear weapons. Israeli leaders say "all options are on the table," a clear reference to a military strike, if they determine that other measures have failed.

"You are not going to make a deal with the Iranians, not under their current leadership," Rabbi Hier said.

Iran has warned it would hit back at Israel if it is attacked, also threatening to strike at American interests in the region.

Ahmadinejad called Israel "a corrupt, anti-human organized minority group standing up to all divine values."

"Today, confronting the existence of the fabricated Zionist regime is in fact protecting the rights and dignity of all human beings," said Ahmadinejad, with a black and white scarf many Palestinians wear around his neck.

Iran and Israel have been bitter enemies for decades. Khamenei has called Israel a "cancerous tumor" that must be wiped out.

"This is a threat to wipe out the state of Israel," Rabbi Hier said. "We should take these people at their word."

Tensions between Iran and Israel have intensified since 2005, when Ahmadinejad said in a speech that Israel will one day be "wiped off the map."

But Rabbi Hier said he does not "subscribe at all with those who say this is a legitimate form of rhetoric."

"The only way to stop what's happening in Iran is for at least the United States and her allies to say, 'How long are we going to sit by and take this threat?'" he said.

The Iranian president has also described the Holocaust, when 6 million Jews were killed by German Nazis and their collaborators during World War II, as a "myth."

"Most intellectuals in 1939 and 1938 did not think Hitler was serious, they thought they knew better, but they didn't know better, and we paid a dear price that we were not on the right side of history," he said.

The Associated Press contributed to this report.