His warning came in a speech to dozens of Auschwitz survivors the evening before official commemorations marking the 70th anniversary of the Soviet army's liberation of the death camp in Nazi-occupied Poland.
About 300 survivors will gather with leaders from around the world Tuesday to remember the 1.1 million people killed at Auschwitz-Birkenau and the millions of others killed in the Holocaust. Leaders expected include the presidents of Germany and Austria, while the United States is sending a delegation led by Treasury Secretary Jack Lew, who is an Orthodox Jew. Lew's family left Poland before World War II.
Spielberg, the Oscar-winning director of the 1993 Holocaust film "Schindler's List," was introduced by an 81-year-old survivor, Paula Lebovics, who praised him as "a man who has given us a voice in history."
In a short speech, Spielberg spoke of how his own Jewish identity evolved, first as a boy learning to read numbers from the numbers tattooed on the arms of survivors, and as an adult when he filmed "Schindler's List" in Krakow.
But he warned of "anti-Semites, radical extremists, and religious fanatics" who are again provoking hate crimes -- a warning that comes after radical Islamists massacred Jews at a kosher supermarket earlier this month in Paris.
Spielberg also noted that there are now Facebook pages that identify Jews and their geographic locations with the intention to attack them, and a growing effort to banish Jews from Europe.
"These people ... want to all over again strip you of your past, of your story and of your identity," he told them. He stressed the importance of countering that hatred with education and preserving Auschwitz and other historical sites.
Earlier in the day some of the survivors traveled an hour and a half by bus from Krakow to Oswiecim, the town where the Auschwitz-Birkenau State Museum is located. There they prayed for their murdered loved ones amid the barracks and barbed wire of the former Nazi death camp, with one survivor crying out in a pained voice: "I don't want to come here anymore!"
Rose Schindler, 85, who was one of 12 survivors from a family of more than 300 people, returned once 20 years ago but said she wanted a final visit to mourn her parents and four siblings who were killed in the Holocaust. She was separated from them upon arrival in Auschwitz with no time to say goodbye and survived because she was selected to do slave labor.
"I have no graves for my mother and sisters and brother, my father. So this somehow is a way to say goodbye," Schindler said.
Together, several of the survivors said kaddish, or the Jewish prayer for the dead, next to the infamous "Arbeit Macht Frei" sign that hangs above the entrance to the camp. That translates into "work makes you free," a cynical statement given that the Nazis killed most of their prisoners.
Marcel Tuchman, a 93-year-old survivor of Auschwitz and three other Nazi camps, reflected on the unspeakable suffering of the Jews, Gypsies, homosexuals and others who were tortured and executed at Auschwitz, many in gas chambers.
"The overwhelming statistics are not the stories to be told," Tuchman said. "The stories could only be told by the victims. Unfortunately their voices were silenced by gas and the crematoria, so we are here, the survivors, to speak for them and honor the memory of their suffering."
Mordechai Ronen, an 82-year-old survivor from Hungary who now lives in Canada, made the trip very reluctantly and said he wasn't sure he had the strength to handle it emotionally. After the survivors prayed in Hebrew he cried out, "I don't want to come here anymore!"
The concentration camp was liberated by the Soviet army on Jan. 27, 1945, in the last months of the war. The Soviet advance from the east forced the Nazis to retreat from occupied eastern Europe to Germany and they took many of their prisoners to kill along the way. However, they left several thousand behind, among them children and prisoners close to death.
The World Jewish Congress and the USC Shoah Foundation helped bring the survivors to Auschwitz for the anniversary. Inspired by making "Schindler's List," Spielberg founded the Shoah Foundation, which has collected video testimony from more than 53,000 Holocaust survivors.