The SA U18 'A' side started brightly and forced their French opponents back into their own half for much of the opening 20 minutes.
The French defence scrambled desperately at times, and it was no surprise that they were penalised on three occasions at the breakdown where they tried to stop the SA team from getting quick ball out wide.
Flyhalf Liam Koen slotted three penalty goals from close range to give his side an early 9-0 advantage.
However, they suffered a setback when lively scrumhalf Emrique Liedeman was forced to leave the field with a knee injury, and he was replaced by his WP team-mate Asad Moos.
The French forwards dominated the latter part of the first half, laying a fine platform which yielded two tries. Left wing Jon Echegaray slipped through a tackle out wide to get their first points on the board, and he was followed by strongly built hooker Babtiste Narmand, who profited from a lineout maul.
Pivot Yanis Brillant succeeded with the angled conversion kick to hand the French a narrow 12-9 lead on the stroke of halftime.
The French forwards grew in confidence after the break, however, SA U18 'A' would be disappointed with the number of missed tackles.
France No 9 Thibualt Motassi Dibongue was sent clear to run in for the first of two converted tries after they won back a contestable kick.
Hard-working SA U18 'A' hooker Juan Smal scored the first of his side's two second-half tries shortly after the visitors stretched their lead to 19-16.
Replacement back Xan Mousques then made it 26-16 when he burst through a couple of missed tackles, before Divan Fuller scored SA's second try to make the final score 26-23 in favour of the French.
Scorers:
SA U18 A 23 (9) - Tries: Juan Smal, Divan Fuller. Conversions: Liam Koen (2). Penalty goals: Koen (3).
France U18 26 (12) - Tries: Jon Echegaray, Babtiste Narmand, Thibualt Motassi Dibongue, Xan Mousques. Conversions: Yani Brillant (2), Oliver Cowie.