In an apparent response to an administration proposal to lift the prohibition against arms sales to Argentina, Sens. Edward M. Kennedy (D-Mass.) and Alan Cranston (D-Calif.) have asked Secretary of State Alexander M. Haig Jr. to look into human rights violations in the South American nation.

The two Democrats, in a joint letter, requested that Haig intervene "on behalf of political prisoners and those men, women and children who have 'disappeared' in Argentina" during recent years.

"Since the military coup in 1976, up to 15,000 individuals have been seized by security forces and then 'disappeared,'" the letter continued. "Just this past week, two more were abducted by Buenos Aires provincial police, held incommunicado, and tortured before being released."

In a related action, Sen. Harrison A. Williams Jr. (D-N.J.) said Argentina has promised to release the names of men and women who have disappeared or died in that country as a result of political unrest. Williams, part of a delegation that visited the country last month, said he had received the pledge during a meeting last week with Argentina president-designate Gen. Roberto Viola.

"It's quite clear from the actions of the president-designate and from comments he made this past week that he is serious about improving ties with the United States and determined to improve the human rights climate," said Williams.

Kennedy and Cranston provided Haig with a list of 12 "particularly humanitarian cases" and asked the secretary to take them up with Viola, who was in Washington for meetings with President Reagan and other officials last week.

But the letter appeared to have a broader purpose, taking great care to lay out the reasons for the ban on arms sales and the history of human rights violations in Argentina.

Kennedy and Cranston were sponsors of the sales ban, first imposed in 1978. Their letter was the first congressional response to the Reagan administration's proposal to lift the ban. It was apparently calculated to gauge administration response to the human rights issue, and to signal their continued concern over the issue.

"We believe there will be significant congressional and public opposition to U.S. military aid to Argentina until its military junta accounts for the disappeared, releases political prisoners and respects the rights of its citizens," the senators wrote.