According to corroborating sources, this statement was meant to avoid severing ties with the Israeli prime minister, who contested the role of mediator claimed by Paris in the search for a hard-fought ceasefire in Lebanon, announced on Tuesday evening by Joe Biden and Emmanuel Macron.
The article says France says it’s about jurisdiction, but specifically about the idea that a head of state has diplomatic immunity.
If Israel was a signatory that argument couldn’t apply because they would have agreed to be subject to the ICC.
Eta more context: https://www.lemonde.fr/en/international/article/2024/11/28/why-france-offered-netanyahu-concessions-over-icc-arrest-warrant_6734435_4.html