The 24-year-old has just one year left on his current deal with Bundesliga champions Bayern, with speculation in Spain claiming the midfielder has already agreed a €25 million [£20m] deal.
Although he recently rejected rumours he had signed a five-year deal at the Santiago Bernabeu, Kroos has now admitted he has made a decision about his next club.
"I've made a decision and can't say," Kroos told TZ Munich. "I read things. It's not hard to find out. But I'm saying there is nothing done.
"First I want to play the World Cup and when finished my decision will be known. I’ll say it myself. Before then there is nothing. There’s one week of the World Cup left and then we'll know more."
Kroos has been linked with a move to Manchester United in the past, but dismissed the speculation at the end of last season.
The midfielder is currently with the Germany squad at the World Cup, with Joachim Low's men set to face hosts Brazil in their semi-final clash in Belo Horizonte on Tuesday.
Regardless of the result, Kroos will remain with the national team until the weekend, with the third-place play-off and final set for Saturday and Sunday respectively.