Respected German journalist Raphael Honigstein has announced on twitter the following:

"Dortmund have told Lewandowski he won't be sold to Bayern this summer. Smart decision, imo, even if they miss out on €25m in the process. sends out a strong message: money isn't everything. Dortmund encouraging foreign bids, obviously. but chance of Lewandowski going anywhere else [besides Bayern] is zero, imo."

"I don't see this as a negotiating ploy. Watzke [Dortmund's CEO] categorical about this. ** Dortmund have made their decision"**

Imo This is fantastic news! Didn't think they had it in them to give up such a fee but they are making a stance that they will NOT be forced to sell if they do not want to!
Great club

Lets see how Lewa will perform knowing this. But its good that they won't sell to Bayern

Honestly, Dortmund would be fools to sell Lewa to Bayern. First of all, it's fantastic that they are saying that they won't sell him to Bayern. Secondly, it's best for Dortmund if Lewa goes to a club that ISN'T Bayern, but the chances really are slim. But the most important fact to take from this is....

Next summer, Lewandowski will be available as a free agent. O.O

So I think Dortmund are bound to sell him by next winter.

they have in their hands the best natural striker in the world right now, selling him to their rivals and for that amount would be a very big mistake to make.

@Dynastian98, they better make him sign another contract

@Joe

Doubt he would want to. He's just been denied a move to his preferred club, and I don't think he's gonna be too fond of Dortmund anymore. I don't think Dortmund fans are too fond of him either anymore.

this or next summer he will go to Bayern .

"We have communicated to the player and his advisers that we will not agree to a transfer to FC Bayern this summer," Zorc told Kicker.
Arsene now is your chance make a a bid for Lewa or Reus!

Yay :)

Just to be clear, he and everyone around him has made it absolutely clear that he has already signed a pre-contract with Bayern and will NOT go anywhere else. As such, he will leave on a free to Bayern next year (which I'm sure they'd be devastated to hear). It's a win-win for Bayern and a lose-lose for BVB.

Of course, it is a gamble. As @raimondo intimated, there is always a chance this could turn into a Llorente situation. They are putting their faith in his professionalism as can be seen by this quote:
"There will be with him now perhaps a small phase of disappointment," said Zorc. "But then he will deliver his usual performance, as does a professional with character... and Robert has a whole lot of character."
Moreover, he will also want to maintain his form and professionalism in order to ensure that Bayern remain interested.

Perhaps they saw the folly of what Arsenal went through last season and have chosen to make a principled stance. Good for them.

@Footaholic

But at the same time, they are losing out on 30-40 Million Euros. :/

They do have a lot of young talent, so maybe Klopp can remedy the problem of Lewa and Gotze's vacancies. Or they could use the money from Gotze and Lewa's transfer to buy new players. Burak Yilmaz and Christian Eriksen have both been linked to Dortmund, so they could both be fantastic options.

^^ I hope they buy those two so that they leave Bernard open for a Spurs switch... O:)

@Lodatz

And at the same time, do Spurs need Bernard? They seem to be well talented in their midfield already. Perhaps they should take a look into Wellington Nem from Fluminese, as you can potentially replace Bale with him.