"If states are unable to guarantee such protection, the international community must intervene with the juridical means provided in the United Nations Charter and in other international instruments," he said.
He called human rights "the common language and ethical substratum of international relations", and added that promoting human rights was the best way to eliminate inequalities.
"Indeed, the victims of hardship and despair, whose human dignity is violated with impunity, become easy prey to the call to violence, and they can then become violators of peace," he said in an apparent reference to social causes of terrorism.
Pope Benedict called for religious freedom to be protected against secularist views and against majority religions that sideline other faiths -- an apparent reference to Muslim states where some Christian minorities report discrimination.
"It should never be necessary to deny God in order to enjoy one's rights," he said.
Diplomats from some 200 states gave him a standing ovation when he ended his speech by reading the phrase "peace and prosperity" in the six official languages of the United Nations - English, French, Spanish, Arabic, Chinese and Russian.
Later, in the UN meditation room, he met UN staffers and wrote in the visitors' Golden Book a quote from the Prophet Isaiah: "Erit opus iustitiae pax" - Latin for "Justice will bring about peace".
He stopped to touch a tattered UN flag that was flying at UN headquarters in Baghdad when a car bomb killed 22 people including 15 UN staff in 2003. Among the dead was the UN mission chief, Brazilian Sergio Vieira de Mello.
Later on Friday, the German-born Pope visited a New York synagogue to offer his greetings at the start of the Jewish Passover holiday. Rabbi Arthur Schneier wished him a "heartfelt Shalom" and praised his commitment to improving relations between Catholics and Jews.
He was also due to visit a Manhattan parish founded by German immigrants in 1873.
The Pope arrived in Washington on Tuesday on his first visit to the United States as pontiff.
On Thursday, he held a surprise meeting with victims of sexual abuse by priests in a bid to heal scars from a scandal that deeply tarnished the Catholic Church in the United States.
Some three dozen protesters outside the UN headquarters held banners including one reading "Child sexual abuse is worse than terrorism".
