The Germany international has been in fine form so far this season, but is adamant that he still has room for improvement.
"I can't deny that I'm playing some of the best football of my career. I have really made a step forward and a lot of things are going well at the moment," the 23-year-old told Bild.
"However, I have not reached the end of my development yet. I cannot afford to sit back and rest on my laurels now."
Kroos then went on to stress that Bayern is determined to win silverware this season to give head coach Jupp Heynckes a worthy farewell.
"He deserves a great farewell. We should win at least one trophy for him. We are all desperate to win a major title again. We have not experienced the feeling of winning something for two years now.
"We all want to end this season on a high. Not just for the team, but also for Jupp."
Heynckes will make way for Pep Guardiola at the of the season, and is expected to retire once he leaves Bayern.