Johar made the revelation during a chat with an Oye 104.8 FM radio host.
When the host asked the filmmaker who is the one actor in front of whom he cannot gather courage to open his mouth, Johar said: "Salman Khan! When he came on my show 'Lift Kara De', I was sitting in my black suit. He was very animated, it was a very serious show. Salman said, 'I am not going to sit here, I want to sit on the floor and you will also have to sit on the floor'.
"I am very scared of Salman for some reason, I don't know why, though he has been very wonderful to me, he is close to my family from a very long time, but I get nervous in front of him."
Johar worked with Salman in his 1998 directorial debut "Kuch Kuch Hota Hai". The movie also featured Shah Rukh Khan.
Johar, who recently launched three newcomers - Siddharth Malhotra, Varun Dhawan and Ali Bhatt - through "Student Of The Year", says the youth brigade aspires to be like Shah Rukh, but their aim shouldn't be that.
"These kids want to be like Shah Rukh, I just told them the way SRK shoots, takes the light, does not fumble even once and controls the camera with his eyes... no one, I repeat no one, can ever do that! There is only one Shah Rukh Khan," he said.