Former Colombian President Cesar Gaviria took office Thursday as secretary general of the Organization of American States, predicting that Haitian democracy will be restored but stopping short of endorsing President Clinton's invasion plan.

"President Aristide will return to Haiti," Gaviria told the large gathering assembled at the ornate OAS headquarters. "That is the desire of the people who elected him and the unbending will of the international community."Gaviria, who stepped down as Colombian president on Aug. 7, was elected last spring to a five-year term as head of the 34-nation organization. He had the strong backing of the Clinton ad-min-is-tra-tion.

Gaviria pledged that as secretary general, he will be "the most devoted fighter for liberty, democracy, peace, prosperity, integration and the well-being of all the peoples of the Americas." He also called for the creation of a free trade zone throughout the hemisphere.

On Cuba, he said that "no one doubts" that Cuba must undertake reforms leading to the "restoration of a pluralistic regime and of public liberties."

Secretary of State Warren Christopher was among the various heads of government and foreign ministers who attended today's ceremony.

The festivities were held amid U.S. plans to lead an invasion of Haiti, and U.S. officials said it was unfortunate that the transition at the OAS was occurring at the same time.

The officials noted that maintenance of peace in the hemisphere is a principal OAS goal. Several member nations, including Mexico, strongly oppose the planned invasion.

Both the OAS and the United Nations have tried unsuccessfully to reinstate constitutional rule in Haiti through economic and other pressures.

The United States normally shies away from endorsements in elections for secretary general, but lobbied hard on Gaviria's behalf during the campaign earlier this year for a successor to Brazilian diplomat Joao Baena Soares.

The U.S. ambassador to the OAS, Hattie Babbitt, praised Gaviria in an interview Wednesday.