The 34-year-old actor, who recently delivered the box-office hit "Ae Dil Hai Mushkil" says that the father-son relationship is "one of complete reverence" and that he has never crossed a "certain line" with Rishi.
"I am closer to my mother. I feel that Dad modelled his relationship with me on the one he shared with his own father.
And it is true that I have never crossed a certain line with him.
"But there is no sense of loss or vacuum here. I do wish sometimes that I could be friendlier with him or even spend more time with him," Ranbir writes in the foreword.
The actor goes on on to say that he would not want to share a similar relationship with his own children in the future and unlike his father, spend more time with them.
"Sometimes I wish I could just pick up the phone and ask him, 'Dad, how are you doing?' But we do not have that. We do not have a phone relationship.
"When I get married and have children, I would want to change that dynamic with them. I don't want my relationship with my children to be as formal as the one I have with my father. I want to be friendlier, be more connected, spend more time with them than he did with me," he writes.
Despite the formal set up of their relationship, Ranbir says that he loves his father "dearly", and always looks up to him for inspiration.
"I love my father dearly and have immense respect for him.
I'm inspired by him and never want to let him down. I know he has only my best interests at heart. He also takes care of the financial side of my work. So we are more connected now.
"His confidence in me and my work makes me take pride in it. I persevere that much harder because of this. His belief and his encouragement are important to me," the 'Rockstar' actor writes in the book.
Ranbir, however, steered clear of commenting on Rishi Kapoor's Twitter personality, but added that his father is a "straight arrow".
"I do not have a take on his Twitter personality. All I can say is, so long as he is being honest and having fun, it's his prerogative. Social media is something very personal.
"Of course, he gets himself into a spot sometimes with his frank speak, but I know he has no agenda and no hidden motive.
My father is a straight arrow," he writes.
The HarperCollins book, co-written by Rishi Kapoor and Meena Iyer, is available for pre-order online and will be launched officially here on Tuesday.