President Reagan Thursday urged the Organization of African Unity to "play an even more active role" in settling regional wars in Southern Africa and the Western Sahara.

The president made the remark in greeting President Moussa Traore of Mali, new chairman of the organization, on a state visit to the White House.Reagan said that since Traore had become chairman of the OAU in May he had "already demonstrated interest in helping promote regional settlements" in the two troubled areas.

"We hope the OAU can play an even more active role in solving those regional problems and play a key role in promoting development in Africa by encouraging economic reform and cooperation," he said.

Traore, in his response, said he was "convinced . . . that our discusions will enable us to make progress in the search for a solution to the problems which are of concern to both our sides."

As he posed for photographs with Traore before their closed meeting, Reagan responded to a question about human rights in Africa by saying, "I think we are sitting beside a man in whose country that is a major goal."