The actor is currently doing a promotional tour for the action thriller co-starring Katrina Kaif.
He told the Hindustan Times: "I'm so fed up. Ek Tha Tiger round the clock promotions with no time to breathe, and then the advice that any charity work at this time will look like a publicity gimmick. How frustrating is that?
"Of course I'll use my star power for my NGO - and my film. At least I say that I'm contributing five percent of everything I earn towards the NGO's work.
"What angers me is when people expect me to come for events for free, trying to use the charity card. If I'll keep doing everything for free, how will I fund my NGO?
"Just yesterday we organised a cataract camp. We are doing operations for 40 to 45 people every day. What do others do - just talk?"
Khan continued: "Even when I campaigned for the release of Sarabjit Singh who's lodged in Pakistani jail, I only had good intentions. But I've had to put that on hold because I'm being told that, close to the release of Ek Tha Tiger, it'll look like a gimmick.
"If I take it up after 5 to 6 months, you'll say it's a publicity stunt for Dabangg 2. Bloody frustrating."
It was reported last week that tickets for Ek Tha Tiger will be the most expensive sold for any film, because of Khan's popularity.
Khan has admitted he does not want to do a publicity tour in India's small towns in case fans injure themselves in the excitement.