James Hook scored Wales’ only try on the stroke of half-time as they struggled for accuracy in the face of a powerful French defence.
France had eased into a 17-0 lead with tries from Jerome Thion and Pierre Mignoni before Hook struck.
And they sealed the win after the interval with further tries from the winger Aurelien Rougerie and hooker Sebastien Bruno, who scored with the final play of the game.
Jenkins said: “The difference today was not the way we have played but between the ability to be clinical in the finishing process.
“There was a lot of creative effort from us but not the clinical edge we need to score tries against teams like France.
“We have made improvements. We will grow as a team but the difference today was that we have seen a side who have shown a clinical edge and that is something we have to grow into our game.
‘‘We have talked positively in the changing rooms. We are hugely disappointed but it is not the World Cup yet. France are the third best team in the world but we have been competitive in every aspect apart from finishing.”
The matches have run out now but Jenkins is confident Wales can develop in training between now and their World Cup opener against Canada on September 9.
“We have learned lessons from France. We are not where they are. The next challenge we have got is Canada and it is a huge game for us.”
Asked whether he thought there is too much work to do in too short a period of time, Jenkins said: “No, I don’t.
Bernard Laporte made 11 changes from the victory over England in Marseille and experimented with three players out of position, with Serge Betsen taking over as captain.
Laporte said: “What is reassuring is that despite changes, the players played in the same spirit. But to win the World Cup we need to do it again from September 7 (the opening match against Argentina).
“It was difficult out there. I think our defence was excellent and there was a real desire to move the ball, a real desire in both defence and attack.”
Tries: Hook. Cons: Hook.
Morgan, M. Jones, Robinson, G. Thomas, S. Williams, Hook, Peel, D. Jones, Rees, Horsman, Gough, A. Jones, J. Thomas, M. Williams, Popham. Replacements: Parker for Morgan (61), Sweeney for Hook (70), Phillips for Peel (41), Jenkins for D. Jones (41), R. Thomas for Rees (46), W. James for A. Jones (63), Charvis for M. Williams (51).
Tries: Thion, Mignoni, Rougerie, Bruno. Cons: Beauxis 4. Pens: Beauxis 2.
Heymans, Rougerie, Jauzion, Skrela, Clerc, Beauxis, Mignoni, Mas, Szarzewski, De Villiers, Chabal, Thion, Betsen, Martin, Harinordoquy. Replacements: Dominici for Rougerie (73), Traille for Skrela (63), Elissalde for Mignoni (41), Bruno for Szarzewski (41), Poux for De Villiers (54), Pelous for Thion (41), Dusautoir for Harinordoquy (48).
Wayne Barnes (England).