Tuchel’s men begin their season with the Bundesliga season opener against RB Leipzig in the German Super Cup on Saturday, which is not until next weekend.
The former Chelsea manager said, “We’re working hard on it… It’s no secret.”
“But there is no decision yet. Until there is an agreement, the coach will not talk about it, because it is not his player.”
Kane scored 280 goals in 435 games for Spurs and is also England’s all-time top goalscorer with 58 international goals.
However, he is yet to win any major trophy at club or international level.
Silverware is almost guaranteed at Bayern, having won 11 consecutive Bundesliga titles.
But the German giants were in dire need of a striker after struggling to replace Robert Lewandowski last season.
Bayern were knocked out by eventual winners Manchester City in the quarter-finals of the Champions League and won the Bundesliga title on goal difference after Borussia Dortmund surrendered on the final day.