The pontiff, addressing the U.N. General Assembly on his first papal trip to the U.S., said the organization's work is vital. But he raised concerns that power is concentrated among just handful of players.
"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.
"The pope's address to the U.N. General Assembly focused on peace and development, and touched on the issues of security, freedom, poverty, the rule of law and the responsibility of the world to protect victims of grave human rights abuses," said CBS News foreign affairs analyst Pamela Falk from the U.N.
"His address emphasized the Holy See's support for the U.N. and defined the role of the Church in the world as a moral authority, calling for the world to guarantee human dignity and religious freedom," Falk added.
The U.N. setting contrasted dramatically with the intimacy of a meeting Thursday, at which Benedict prayed with weeping victims of childhood sexual abuse by priests.
The pope took an early morning flight from the Washington, D.C., to New York City. He was greeted by New York Cardinal Edward Egan and taken to a helicopter for the ride into Manhattan.
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, New Jersey, 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."
Before the pontiff's speech, Benedict and Secretary-General Ban Ki-moon met alone for 15 minutes.
"It's a reminder that he speaks not just as the sovereign of a tiny little speck of earth inside the city of Rome, but he speaks as someone whose voice is heard as a spiritual leader by a fifth of humanity," said Professor Peter Pham of James Madison University.
Pope Benedict took that voice late today to a Synagogue on the eve of Passover. He's the first Pope to ever do so on U.S. soil, reports CBS News national correspondent Byron Pitts.
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. Later Friday, he was to visit a synagogue and meet with leaders of other Christian denominations.
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.
On Thursday, Benedict met privately with abuse victims in Washington between an open-air Mass at Nationals Park and a meeting with Catholic educators.
The Rev. Federico Lombardi, a papal spokesman, said that Benedict and Boston Cardinal Sean O'Malley met with a group of five or six abuse victims for about 25 minutes, offering them encouragement and hope. The group from O'Malley's archdiocese were all adults, men and women, who had been molested when they were minors. Each spoke privately with the pope and the whole group prayed together.
One of the victims, Bernie McDaid, told The Associated Press that he shook the pope's hand, told him he was an altar boy and had been abused by a priest in the sacristy of his parish. The abuse, he told Benedict, was not only sexual but spiritual.
"I said, 'Holy Father, you need to know you have a cancer in your flock and I hope you will do something for this problem; you have to fix this,"' McDaid said. "He looked down at the floor and back at me, like, 'I know what you mean.' He took it in emotionally. We looked eye to eye."
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."
Both men have worked with church officials in the aftermath of the crisis, and met with a new office established by U.S. bishops in response to the scandal.
Their sentiments were echoed by O'Malley, who called the meeting "a very moving experience for all who participated."
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.