The 33-year-old Bulgaria international is in discussions with the Spanish club about a move to Catalunya after becoming surplus to requirements at the Reebok Stadium
The Bulgarian winger is reportedly one of the club's highest earners, and has had only a bit-part role to play this season, participating in 14 of a possible 26 matches with eight of those appearances coming off the bench.
"We've got to face the facts. Martin is in the latter years of his career and earns a lot of money at this club," Freedman told BBC Radio Manchester.
"I feel the best thing for the club is to bring in some new, young blood.
"That's where we are and I hope everybody understands this decision."
Petrov joined the Trotters from Manchester City on a free transfer in the summer of 2010, going on to make 85 appearances and scoring 12 goals in the process.