Bayern confirmed on Tuesday that the talented 20-year-old will move to the Allianz Arena in the summer in a £32million deal, making use of the release clause in his contract.
Sammer, a former Dortmund captain and manager who is now at Bayern, says Gotze rejected interest from elsewhere before deciding to join the newly-crowned Bundesliga champions.
The Germany international has previously been linked with a host of top clubs, including Manchester United, Barcelona and Real Madrid.
Sammer told Sky Deutschland: "You have to be aware that Mario Gotze has had incredible offers from other clubs. Those offers were really mad!"
Bayern announced the deal ahead of their UEFA Champions League semi-final against Barcelona on Tuesday night, which they won 4-0, while Dortmund host Real Madrid in the first leg of the other tie on Wednesday.
Sammer admits the timing was not ideal, while also confirming Bayern have not spoken with Dortmund about the move.
He added: "Of course, the publication of this transfer has not been so ideal. We intended to go public with it just after the UEFA Champions League semi-final fixtures.
"We haven't been in touch with Borussia Dortmund over it. Why should we? Mario Gotze has got a contract release clause and he is making use of it."