Le Mans were leading 2-0 when Milan Robin struck in the 91st minute, triggering angry scenes in the stands from Bastia fans, whose relegation to the third division had already been confirmed.
"The match between SC Bastia and Le Mans FC has been stopped and will not resume," Ligue 2 said in a statement on X.
"A disciplinary committee of the LFP will meet in the coming days to decide the fate of the match."
Le Mans have attracted high-profile investors in recent years, with tennis great Novak Djokovic and former Formula One drivers Felipe Massa and Kevin Magnussen buying stakes via Brazilian group OutField last year.
Real Madrid and Belgium goalkeeper Thibaut Courtois also invested in the club in February through NxtPlay Capital, the company he co-founded.