She also said that she hoped to live up to the personal vow she made when she became a goodwill ambassador four years ago, to do everything possible to help refugees all over the world because "they deserve every bit of our effort."
Brad Pitt, who for the past several months has been linked to the actress, did not attend the event.
At the dinner, Jolie, 30, quoted from the preamble to the U.N. Charter, which reaffirms "faith in human rights" and said, "the U.N. is the closest thing to fighting for justice."
She added, "I feel very, very privileged to be a very small part of it."
The dinner also paid tribute with a Global Leadership Award to Leonore Annenberg, president and chairman of The Annenberg Foundation, but the 87-year-old Annenberg was too ill to attend.
Still, she and Jolie were praised at the event by Laura Bush, who told the women in a videotaped message: "You've both used your gifts and talents to make the world a better place."