The 26-year-old Frenchman has become a key figure at Stade Velodrome since arriving from FC Libourne-Saint-Seurin in 2006, and his form in the South of France has been said to have attracted interest from several Premier League sides - including Liverpool and Arsenal.
The Gunners have been strongly linked with a move for Valbuena in the last week, with manager Arsene Wenger said to see his compatriot as a potential replacement for Cesc Fabregas or Samir Nasri, should either player leave Emirates Stadium.
However, Deschamps insists l'OM have not yet had an official offer for the 5ft 6in schemer.
"For the two years I have been here, no concrete offer has ever arrived," Deschamps told La Provence. "That doesn't mean Mathieu is not a player of great value.
"Considering our Champions League qualification, I believe the most important thing [for Valbuena] is to remain at Marseille."
But Deschamps admitted that if a sizable offer was tabled for the playmaker, he may well be pressured into a sale by the club's board.
"However, if an attractive offer comes to the officials, I will probably be asked to think about it. It is not the case today."
