The Soviet Union will vote along with the United States and Israel against a PLO bid for membership of the World Health Organization, a senior Palestinian diplomat said Friday. Radio France Internationale quoted Nabib Ramlawi, the Palestine Liberation Organization's representative in Geneva, as saying he was told of Moscow's position by the Soviet ambassador Thursday night. The radio, in a text released to news agencies in Paris, quoted Ramlawi as saying, "The Soviet delegation assured me that this position had nothing to do with Soviet policy toward the Palestinian cause. This policy is dictated purely by the Soviet Union's concern to safeguard WHO."