The reigning champions host Manchester City, who have also already qualified for the knockout stages, in the Group D decider and are in prime position to win the pool as they are three points clear and beat City 3-1 in the reverse fixture at the Etihad Stadium.
However, midfielder Kroos insists Bayern are not taking their eye off the ball, adding that they will be looking to extend their record-breaking run of Champions League wins to 11 games against Manuel Pellegrini's men.
"We haven't secured top spot yet," he is quoted as saying by the Bundesliga's official website. "So again we'll have to be at our best.
"City are a very good side. We can't just rely on the previous result (against them) as it will be a whole new challenge."
Bayern cruised to a 7-0 win at Werder Bremen in the Bundesliga on Saturday, but Kroos is certain the result was a one-off and that they will rarely find matches that easy again.
"You can't really complain after a 7-0 victory. There's little we could've done better," he continued. "I don't actually think that's always the case (that Bayern find it easy).
"We were made work really hard by Augsburg in the DFB Cup on Wednesday for example.
"To be honest, Bremen made it pretty easy for us after going 3-0 down. They didn’t tighten up at the back like other teams, in order to keep the score to a minimum.
"That gave us plenty of room, but we worked hard for our lead in the first place."
Kroos has featured in all five of his side's Champions League matches so far.
