A delegation from the U.S. Department of Justice will visit Vienna on Friday to discuss the agency's decision to bar Austrian President Kurt Waldheim from traveling to the United States, a spokesman for the Austrian Chancellory said. Government sources said the Americans are coming at the request of the Austrian government and will stay one day. Waldheim was barred after a Department of Justice investigation of charges that he covered up his military service in the Balkans in World War II. He has denied allegations that he was involved in war crimes. Austrian Chancellor Franz Vranitzky is scheduled to visit Washington next weekend for talks with President Reagan, members of Congress and others.