It is not immediately obvious whether that is just a statement of the obvious (France has a post-colonial presence military in the Republic of Chad and supports the government), an attempt at denigrating the capabilities of the Chadian forces, or a real accusation of French aircraft doing the striking in the three airstrikes against anti-Chad insurgent forces across the border in Sudan, but that is what the Foreign Ministry of Sudan is saying.
Given that the Chadian Air Force operates only about 20 aircraft (fixed wing and helicopters), and only 2 (of 6 ordered) Su-25A ground-attack aircraft are of any real use in the strike role, it is not surprising that Sudan would claim that the attacking aircraft came from the French Assistance Operation at N'djamena. This deployment operates Mirage F1 fighters in multi-role missions in the defense of Chad.
However, given the obvious identification differences between a Su-25A and a Mirage F1, one would think that the Sudanese claim would be more strongly made (if they had any proof).
What, if anything, the Sudanese are about to do in reprisal remains to be seen. The Air Force of Sudan operates ~20 MiG-29 (depending on maintenance availability), but quality of aircrews and general combat proficiency vastly favors the French if things came to a fight.