Dembele, 20, made a move to Barcelona from Borussia Dortmund in August last year for a reported €105 million.
However, a hamstring injury derailed the France international's season early and he has managed just 12 league appearances – seven of those starts – this campaign.
But Dembele is still planning to prove himself at Barcelona, dismissing any suggestions he could leave at season's end.
"I'm not going to leave after just one season," he told Telefoot. "I signed a five-year contract with Barcelona.
"I'll be here for a long time."
The arrival of Antoine Griezmann from Atletico Madrid in the off-season could further hurt Dembele's chances of game time at Camp Nou.
But Dembele said he expected competition for places at a club like Barcelona.
"It's Barca. It's like that. I'm glad that [Philippe] Coutinho has come in," he said.