"I hope they have worked out their political screenplays in some detail before taking the plunge. I don't think they have. I hope I am wrong. Because politics is no bed of roses," he said.
The lawmaker, who has an acrimonious relationship with his own party's leadership, said both Mr Rajinikanth and Mr Haasan should be clear about why they want to come into politics.
"Rajinikanth and Kamal Haasan should be very clear on why they want to come into politics. Why just Rajinikanth? Even Kamal Haasan is a very good friend of mine. They never sought my advice before plunging into politics. If they had, I'd have warned them about the pitfalls of politics," he said.
Talking about his differences with the BJP, he said he thought he would be given cabinet rank, but a "television actress" was given the position. He said he was subjected to humiliation.
"Look at the way I've been treated by my parent party. I was given to understand that I'd be given cabinet rank. Instead a television actress was given cabinet position. I was only subjected to humiliation and indifference. We actors are brought into political parties to draw in the crowds. But when we do draw in the crowds the party gets insecure about our popularity. It's really a very tricky situation," Mr Sinha said.
"Actors come from a world of glamour. They are addicted to glamour. In politics, there is a lot of power. And power is extremely glamorous. Actors come to politics in the hope of building on their glamour and fame," he added.
But the truth, he says, is somewhat removed from expectations.
Mr Sinha said his "friend" Mr Rajinikanth didn't seek his advice before joining politics. He said he would have advised him against it, as DMK's acting president MK Stalin had a very strong base in Tamil Nadu.
"No, Rajini didn't seek my advice. If he did I'd have advised him against it. Look, it's not going to be easy. M K Stalin has a very strong power-base in Tamil Nadu's politics. He has done a lot for the people. Rajini can't ignore Stalin's position. And why are we only talking about Rajini? He too will find the going really tough," he said.
With inputs from IANS