"Am sure you all will get inspired by Hrithik's efforts! He has made a significant effort towards creating a Swachh Bharat. MyCleanIndia," Modi wrote on his Twitter handle.
His comments came hours after Hrithik Roshan tweeted: "Swachhbharat I started cleaning my own surroundings and learnt so much. Started with my lanes in Juhu.
"2day I pledge 2 keep my home, my roads, my city, my country clean. I also take responsibility 2 teach n empower others 2 follow."
In another tweet, Modi said: "Noted actor Nagarjuna joining Swachh Bharat Mission can draw many others towards our efforts to create a Clean India."
Modi launched the "Swachh Bharat Mission" campaign October 2, the birth anniversary of Mahatma Gandhi.