Dembele, 24, has been free to speak with other clubs since Jan. 1 after moving into the final six months of his deal at Camp Nou.
Barca want to extend his terms but have been unable to reach an agreement with his representative, Moussa Sissoko, who said the Catalan club have been unwilling to negotiate.
"It is intimidation and it doesn't work with us," Sissoko told RMC. "Maybe it works with agents who are part of the Barcelona old boys' network, but that's not the case with me. I am here to defend the interests of my player.
"We're not here to fuel debates on social media, but the truth must be told. Yes, we have certain demands, but we've already shown that Ousmane's career choices aren't dictated by money, otherwise he would not be here.
"If Barca wanted to negotiate, they could have come to the table with us to talk. Except there has been no discussion, just threats of no longer playing him [if he doesn't renew]. That is forbidden and we will assert Ousmane's rights if necessary."
Sources have previously told ESPN that some members of the Barca hierarchy are in favour of banishing Dembele to the stands if he runs his contract down. Coach Xavi Hernandez has said he would be against such measures.
Meanwhile, director of football Mateu Alemany has said that Barca's final offer to Dembele and Sissoko remains on the table but that the club need a response "as soon as possible."
"We don't know what we're going to do, nothing has been finalised," Sissoko added. "But Barca's hierarchy are losing Dembele on their own. Since the beginning, we have shown a desire to negotiate, with certain conditions, of course, but without closing the door."
Dembele joined Barca for over €100 million in 2017 following the departure of Neymar. Injuries have disrupted his four years at the club, but he has been a regular under Xavi since returning from injury at the end of last year.
Xavi has urged him to renew his contract at the LaLiga side and said "well-coached, he could be one of the best players in the world in his position."
Dembele, who has scored 31 goals in 129 Barca appearances, played all 120 minutes as the Blaugrana lost in the Spanish Supercopa to Real Madrid last week.
Barca must now decide what to do with the winger as the stalemate over his contract continues. They are next in action on Thursday, when they travel to Athletic Bilbao in the Copa del Rey.