Prime Minister Benjamin Netanyahu urged the international community Tuesday to take steps against Iran's nuclear program and "not sit idly by" during any attempt to carry out another Holocaust.

"This is a day when the world needs to commit not to allow another genocide and to act so that weapons of mass destruction don't reach the hands of Iran's ayatollahs. Only a combination of crippling sanctions and putting all the options on the table can make Iran stop," Netanyahu told the Knesset, which was marking International Holocaust Remembrance Day.

"We can't stick our heads in the sand. The Iranian regime's emissaries, Hamas and Hezbollah, have already fired thousands of missiles at us, but when there are those who try to belittle or deny those who are warning of the danger, they apparently haven't learned their lesson. The lesson is that the countries of the world must be roused to act against the threat while there is still time."

Netanyahu raised the question of whether the world had learned the lessons of the Holocaust. He noted the uniqueness of the genocide committed against the Jews during World War II, but asked whether the establishment of the United Nations had prevented subsequent genocides.

The answer is no, he responded, citing the genocides in Cambodia, Rwanda and Sudan. "When the world has intervened, it has always been late, and with masses of people paying with their lives," he said.

"Look what's happening in Syria. Despite progress, technology and the flow of information, the world is not stopping in its tracks over the men, women and children who are being murdered indiscriminately. Against this backdrop, can we say with certainty that the world would not sit idly by in the face of renewed attempts to exterminate our people?"

Netanyahu cited recent Iranian threats to destroy Israel and said many people have remained silent in the face of those threats and threats by Hezbollah and Hamas. He also noted remarks attributed last week to the Muslim mufti of Jerusalem, Mohammed Hussein, in which the cleric reportedly referred to the killing of Jews in an end-of-days struggle.

Referring to Haj Amin al-Husseini, the mufti of Jerusalem who took office in the 1920s and later collaborated with the Nazis, Netanyahu said: "Most unfortunate is that there is a tradition of hatred and extermination here. Haj Amin al-Husseini was among the architects of the Final Solution."

The worldwide observance of International Holocaust Remembrance Day officially falls on January 27, the anniversary of the liberation of Auschwitz.

The international observance was designated in 2005 by the United Nations following an initiative by Vice Prime Minister Silvan Shalom when he was foreign minister. Israel's own national Holocaust commemoration day is held the week before Independence Day in the spring.

Also Sunday, opposition leader Tzipi Livni (Kadima ) said Israel does not justify its existence on the Holocaust but on the Jewish people's historic ties to the country.

"There are those who express identification with the people of Israel, but there are those who say that when we saved one people [the Jews], we caused injustice to another people," she told the Knesset. "We need to caution against making such a connection."

She added that Israel was not in danger of destruction. "Our role is to tell parents that the country is a secure place for their children," she said. "With such security, we should demand that the world do what is necessary to prevent those who don't accept the international community's values from obtaining [nuclear] weapons."

Speaker Reuven Rivlin said Israel did not have the privilege of pursuing a policy based on power alone. He added that Israel did not have the right to be apathetic about genocide attempts in Africa, Asia or the Middle East. "We don't have the right to deny the tragedies of other peoples," he said.