Mintzlaff told Sport1 (h/t Tony Mogan at the Evening Standard) that he thinks the 19-year-old is keen to move but fears his club may be priced out of a deal for the striker.
"We are interested in the player, great interest. He listened to it, logically, and is very open to a move. He would like to change (clubs) in summer at the latest. It is not easy. There's Manchester United, Juventus, Borussia Dortmund. There are a few other clubs as well.
"Of course, our club also has certain guard rails and limits. And I have named the clubs that compete, and there may be salary regions that we don't want to go into. (The fee) is still manageable, but the package does not only consist of the transfer fee.
"It's the same cliche again: we can buy everything and we can get everything and we can do everything. Unfortunately, we can't, otherwise Haaland would already be with us."
Haaland has caught the eye after netting 16 goals in 14 appearances for RB Salzburg in the Austrian Bundesliga and also shining in the UEFA Champions League group stages:
The prolific striker is regarded as one of Europe's most talented young attackers and could be snapped up by one of the continent's top teams when the transfer window opens in January.
RB Salzburg sporting director Christoph Freund has said his team had held talks with Leipzig and Borussia Dortmund over a potential move.
"We are involved in all discussions," he said at a press conference. "Of course, we also knew that Haaland was in Leipzig and Dortmund yesterday. Everyone in Salzburg wants the best for him."
There has also been talk of interest from Manchester United. Manager Ole Gunnar Solskjaer, who worked with Haaland at FC Molde, has played down rumours the striker was flying to England for transfer talks:
The Norwegian has also said that Haaland "knows what he wants to do, and he knows what he's gonna do," per Samuel Luckhurst at the Manchester Evening News.
Serie A champions Juventus are also reportedly interested and are ready to pay his €30 million (£25.7 million) release clause, according to TuttoMercatoWeb (h/t Football Italia).
The Guardian's Fabrizio Romano offered an overview of the situation and why Leipzig may still have a chance of landing the youngster:
Fabrizio Romano @FabrizioRomano
...just remember: going to Leipzig would mean business for Red Bull, same ownership of Salzburg and no release clause problems. So, Leipzig (and also BVB) must be considered in the race for Håland as Man United and Juventus. But only the player must and will decide! 🇳🇴 #Haaland
Haaland seems to have his pick of clubs at present, and a move, either in the winter or next summer, looks inevitable as one of Europe's hottest properties prepares to take the next step in his career.