Speaking at a summit of the Nonaligned Movement (NAM) in Cuba, Annan said developing countries had a duty to end the suppression of opposition groups and the media, and to take measures against corruption.
Annan also called for fairer global trade to help reduce the gap between the world's poorest and richest nations.
The NAM brings together 118 countries, including several that have been criticized by human rights groups. The group includes countries such as Zimbabwe, Belarus, Iran, and Venezuela. Many share an anti-U.S. stance.
Iran's standoff with the international community featured prominently at the meeting with Iranian President Mahmud Ahmadinejad calling for the movement's members to show "unity and solidarity."
Ahmadinejad also underlined that the defense of members' territorial integrity was one of the founding principles of the NAM.
Iran faces international sanctions over its failure to suspend its enrichment of uranium. That and its failure to cooperate fully with UN inspectors has raised concerns that it is seeking to develop nuclear weapons.
Venezuela's President Hugo Chavez pledged to support Iran in any confrontation with the United States over Tehran's nuclear program, adding that Iran could count on Venezuela's support should it be invaded.
(AP, Reuters, dpa)