Montpellier's Willemse, 30, has been sidelined since late April and will receive treatment as part of the 26-man group for a two-day camp this week starting on Wednesday, in Marcoussis, to the south of Paris.
Centre Arthur Vincent and winger Gabin Villiere are also included after recovering from fitness issues with scrum-half Baptiste Serin and forward Yacouba Camara joining Willemse on the treatment table.
Six uncapped players have been selected by head coach Fabien Galthie including the Top 14's leading try scorer in 19-year-old Pau centre Emilien Gailleton.
Players from Top 14 semi-finalists, Toulouse, Racing 92, La Rochelle and Bordeaux-Begles are omitted with the last four ties taking place this weekend.
France's next training camp, with 42 players, will take place in July in Monaco.
Galthie will name his final 33-man squad for the tournament on August 21st, six days before Les Bleus' final pre-competition Test with Australia.
Hosts France open their World Cup campaign against three-time winners New Zealand in Paris on September 8th before also facing Uruguay, Namibia and Italy in Pool A.
