The two actors are currently shooting Krrish 3, which is directed by Roshan's father Rakesh.
Oberoi tweeted: "So impressed with @iHrithik. Even with a profusely bleeding cut in the hand, he kept shooting with absolute dedication! Hats off! Inspiring."
Oberoi has described his recurring character Kaal in Krrish 3 as Bollywood's first "super-villain".
The Kismet Love Paisa Dilli star has also praised Roshan for being supportive of his fellow actors.
He said: "When you get that kind of encouragement from your co-star, from somebody who is doing so well, it's a great atmosphere on the set. There is no insecurity, no negativity. It's a great set to be on."
Oberoi admitted in October that he had wanted to disappear after the box office failure of Rakhta Charitra.