U.S. Secretary of State John Kerry also voiced congratulations. He highlighted the organization's role in Syria.
"The Nobel Committee has rightly recognized their bravery and resolve to carry out this vital mission amid an ongoing war in Syria," he said.
Last year, the Norwegian committee awarded the peace prize to the European Union as it grappled with the worst crisis since its founding -- devastating debt and the threat of disintegration.
The award was a salute to the struggling 27-nation union for its work in promoting democracy and reconciliation since World War II.
It is common for the Nobel Peace Prize to go to organizations.
Other large organizations that have won it include the United Nations, Doctors Without Borders, U.N. peacekeeping forces, the U.N. atomic energy agency, the Red Cross and the International Campaign to Ban Landmines.
The Peace Prize is the fifth Nobel Prize to be awarded this week, preceded by honors in medicine, physics, chemistry and literature.
The final Nobel Prize, recognizing achievement in the field of economics, will be awarded Monday.