President Carter urged the Fifth United Nations Conference on Trade and Development (UNCTAD) here today to assure the elimination of poverty. The absence of specific suggestions, however, prompted grumbling among the poor nations assembled on the American role in such an effort.

Carter's message - a three-page statement couched in generalities - was delivered by U.N. Ambassador Andrew Young. The president said priority should be given to increasing food production and improving its distribution to the poorest among the poor.

Complaining delegates compared the general language of Carter's message with a pledge by Japanese Prime Minister Masayoshi Ohira to lower Japan's trade barriers to exports from the poor nations, and to helo to train their technicians.

Young also said that the United States was "not in a position . . . at this time" to contribute to a large common fund that the Third World countries insist is necessary to stabilize raw material prices. He pointed out, however, that the United States supports greater assistance for Third World needs by international agencies.

The conference also heard a warning from World Bank President Robert S. McNamara that progress made in the past 25 years in helping the poor countries is being eroded by "the gathering momentum of trade protectionism."

McNamara blamed the protectionist pressure on a combination of two factors: slower growth in the industrial world, and concentration by the Third World nations on a few, highly visible categories of exports.