"Multilateral consensus," he said, speaking in French, "continues to be in crisis because it is still subordinated to the decisions of a small number."
The world's problems call for collective interventions by the international community, he said.
"The promotion of human rights remains the most effective strategy for eliminating inequalities between countries and social groups, and increasing security," the pope said.
Benedict, only the third pope to address the United Nations, made the remarks after three dramatic days in which he repeatedly discussed America's clergy sexual abuse scandal.
Across from the U.N., several hundred supporters, many of them Hispanic, gathered behind metal police barricades.
"Benedetto!" many shouted in Spanish.
A group of New Jersey Catholics held up a banner for the German-born pope that combined German -- "Willkommen Pope Benedict XVI" -- and English sentiments: "You Rock!"
A small anti-pope contingent included a group calling itself Forum for Protection of Religious Pluralism.
Financial consultant Padmanabh Rao, a Hindu from Woodbridge, N.J., complained that the Vatican is converting people in India to Catholicism.
Queens contractor William Salazar, who identified himself as a Navajo Indian, said Catholic priests "came to America and they killed our children. Now the pope is sending priests all over the world who are raping our children."
The pope's New York visit will also include a visit to ground zero, site of the Sept. 11, 2001 terrorist attacks, and a Mass at Yankee Stadium on Sunday.
It remains to be seen whether Benedict will continue to talk about the sexual abuse crisis. He has been widely expected to broach the subject on Saturday when he celebrates Mass for priests, deacons and members of religious orders at St. Patrick's Cathedral in Manhattan.
Olan Horne, another Boston-area victim who prayed and talked with Benedict, told the AP, "I believe we turned the pope's head a little in the right direction."
Benedict's address to the presidents of Catholic colleges and universities was among the most anticipated of his trip, but was overshadowed by the meeting with victims.
The pope, a former academic, said academic freedom has "great value" for the schools, but does not justify promoting positions that violate the Catholic faith.The Associated Press contributed to this report.