Israeli Prime Minister Benjamin Netanyahu on Sunday denounced a "volcano of anti-Semitism" and international criticism of Israel's war in Gaza, insisting that no pressure would stop it from defending itself.

"If Israel is forced to stand alone, Israel will stand alone," Netanyahu said.

Speaking at a Holocaust Remembrance Day ceremony at the Yad Vashem memorial in Jerusalem, he lamented that when the Nazis killed six million Jews during World War II, his people "were totally defenseless against those who sought our destruction.

"No nation came to our aid," he said as the Israeli flag billowed at half-mast and survivors of the Holocaust prepared to light torches.

"Today, we again confront enemies bent on our destruction," Netanyahu told the large crowd gathered for the ceremony.

One yellow chair sat empty representing the hostages still held captive by Hamas in Gaza.

"I say to the leaders of the world, no amount of pressure, no decision by any international forum, will stop Israel from defending itself."