Flick said that Bayern would be one of the club's interested in signing the striker if he decided to leave Dortmund in the future.
"A lot is possible in life," he said. "I can't rule that out. He has a long-term contract with BVB, but he is a player who is the focus of many top teams.
"If this were to ever materialise, of course it would be another case of a top Dortmund talent leaving to go to Bayern, but it will inevitably be up to Haaland where he goes next."
Dortmund could face a battle to keep Haaland this summer if they fail to secure a Champions League spot next season as they sit four points off the top four after losing to Bayern.
Flick also compared Haaland to Bayern striker Robert Lewandowski, who scored a hat trick against BVB.
The Poland international only needs to score nine more league goals to match Gerd Mueller's record tally of 40 in a single campaign.
"Robert has proven over the years what a world-class player he is," Flick added. "He has proven over the years that he plays at a top level.
"Haaland is a young player who is very hungry for goals. He has tremendous drive, tremendous speed and a strong finish."