The 24-year-old has been linked with a move to Marseille but the Brittany club are desperate to keep hold of him following a season in which he scored 10 goals in 22 Ligue 1 appearances.
De Saint-Sernin told L'Equipe: "I repeat that Romain Alessandrini will not leave Stade Rennais this season."
Alessandrini reported for training today as the squad gathered for the start of pre-season, and their first session under new coach Philippe Montanier.
Also present was new signing Sylvain Armand, newly arrived from Paris St Germain.
The versatile defender, 32, is set for a role in the centre under Montanier and is looking forward to playing his part.
"I want to thank the president and the coach for bringing me to Stade Rennais," he told the club's website. "It's a new page after nine seasons at Paris Saint-Germain.
"It is a club that starts on a sound footing with a new coach. I hope to adapt as quickly as possible to the new coach and also my new team-mates."
Rennes have frequently gone close to major honours in recent years, twice finishing fourth in the league and also reaching the 2009 Coupe de France final, where they suffered a surprise defeat to Guingamp.
"Before arriving here, I had the image of a club who were on course each season but fell away at the last moment," said Armand. "I think there is the possibility to see that course through this season.
"I will try to bring something extra with the experience I have, but I must also adapt to the club."