Argentina and Uruguay, reacting to cutbacks in U.S. aid linked to alleged violations of human rights yesterday rjected American aid worth more than $15 million.

Argentina Defense Minister Gen. Jose Maria Klix said that Argentina will abandon $15 million in U.S. military sales credits for fiscal year 1978, leaving $700,000 in military training grants as the nation's only assistance from the United States.

In Montevideo, Gen. Jose Cardozo, Uruguay's minister of planning, coordination and information, said his government will reject "any type of economic aid from the United States" in the future. Uruguay received $220,000 in U.S. development funds in the past fiscal year.

The U.S. Congress voted last year to suspend military aid to Uruguay, citing alleged violations of human rights by Uruguay's military government. Last week Secretary of State Cyrus Vance told Congress that military aid to Argentina was being reduced from $86 million to $15 million for the same reason.

Neither Argentina nor Uruguay has been a major recipient of U.S. aid. Uruguay has a U.S. Agency for International Development mission, and its decision to decline further funds will end a $195,000 training program now is effect and $25,000 in economic development projects. Argentina has no American economic aid programs other than the military assistance.