PARIS, JULY 28 -- Foreign Minister Roland Dumas expressed hope today that France's release of a Lebanese man and four accomplices convicted of terrorism ordered by Iran will lead to freedom for all Western hostages in Lebanon.

The French hopes coincided with a prediction in the Tehran Times, an English-language newspaper close to supporters of President Ali Akbar Hashemi Rafsanjani, that Friday's decision by President Francois Mitterrand could "facilitate the Islamic Republic's humanitarian efforts to convince the Lebanese groups to free the hostages."

Neither Dumas nor the Iranian newspaper provided any concrete indication that the shadowy Lebanese groups that hold U.S. and European hostages are ready to let them go. But both seemed to be saying that a step such as liberating Anis Naccache and the other four terrorists, all of whom had been in French prisons for the past 10 years, could make release of the remaining hostages more likely.

Sixteen Western hostages, including six Americans, are believed to be held in Lebanon by Moslem radicals connected with Hezbollah, the Iranian-backed Shiite militia. The longest held captive is Terry Anderson, chief Middle East correspondent for the Associated Press, who was kidnapped March 16, 1985.

Asked what France expects in return for freeing Naccache, Dumas told the Paris newspaper Le Monde: "General pacification, a lowering of tensions in the region and, I also hope -- we are working on it -- the release of all Western hostages still held."

The imprisonment of Naccache, 40, had been a bone of contention between France and Iran since July 18, 1980, when he and his four accomplices botched an attempt here to assassinate Shahpour Bakhtiar, Iran's prime minister before the 1979 Islamic revolution. Bakhtiar escaped unhurt, but a French policeman and a passerby were killed, and a second policeman suffered wounds that paralyzed him for life.

Iran maintained a particular interest in Naccache, French anti-terrorism experts said, because he had been sent to Paris by Iranian officials close to the late Ayatollah Ruhollah Khomeini to kill Bakhtiar.

It was against that background that Dumas suggested that Naccache's release could smooth the way for efforts to free Western hostages.