Any doubts that handicapped Americans are becoming a political force were dispelled by the parade of Cabinet officiers before the White House Conference on Handicapped Individuals yesterday.

The secretaries of Transportation, of Labor, of Health, Education and Welfare, of Housing and Urban Development apologized, praised and promised in speeches to more than 3,000 handicapped people and their friends.

They apologized for past injustices. They praised the courage of handicapped people. They promised new programs and money.

"We're grateful to you for allowing us to prove we can be useful," said HUD Secretary Patricia Roberts Harris. She announced a new Office of Independent Living for the Disabled and pledged 11,000 new housing units for the handicapped.

The Department of Labor "will wholeheartedly join" the handicapped people's struggle for civil rights, Secretary Ray Marshall said. "We've got to be concerned about creating jobs as well as enforcing laws against discrimination."

Announcing the Transbus program of equipping buses with lower floors and boarding ramps, Transportation Secretary Brock Adams said, "We've done what we should have done long ago."

HEW Secretary Joseph A. Califano Jr pledged to enforce recently issued regulations requiring all HEW-funded institutions, including schools and hospitals, to eliminate physical and programmatic barriers to the handicapped.

The conference, which opened Monday with a pledge from President Carter to end discrimination, had all the trappings of a political party convention.

The 780 delegates and 2,000 non-voting participants were chosen at state meetings.