It is claimed the Blues have triggered Werner's release clause, thought to be in the region of £54million (€60m), to win the race for his signature.
However, Mintzlaff would not be drawn on those suggestions while speaking to Sky Sport.
Mintzlaff said: "We are concentrating on the final sprint of the league. We want to go to the Champions League. That is the only thing we are currently discussing with Timo.
"It was important for us that we extend the contract with him. We did that last summer because of course, it is important for our young club that no player moves free of charge.
"Of course, there was this exit clause that we put in the contract to give him the opportunity to take the next step.
"Now Timo Werner is sitting in the driver's seat, not us anymore. So far, Werner has not exercised the clause, nor has any club sent us a transfer contract.
"We haven't had an exchange [with Chelsea] yet. Accordingly, we have nothing to report. Timo Werner is a player for RB Leipzig. He signaled a few weeks ago that he was busy with a transfer. Right now nothing is dry."
Mintzlaff was also asked about whether they would continue in this season's Champions League, which had seen half of the last-16 ties completed when the coronavirus pandemic brought the campaign to a halt, with Werner in the event of a transfer being confirmed.
"We can only discuss when we know when the Champions League is going to take place," he replied. "It won't be decided until mid-June."