The 64-year-old actor - who is an associate producer of the shows about the Belgian detective - has just six of Agatha Christie's stories left to film, but told The Sun he would never want to let fans down by making a bad quality version.
David said: "I only have six more stories to do and that will be the complete works of Hercule Poirot - I'm desperate to do it, while God gives me life."
But he added: "I'd probably say no if they asked me to film the final six on a limited budget.
"There are people collecting these box sets around the world. I don't want somebody to take out a film and think, 'If that's bad quality, I may not watch another'.
"Being an associate producer has allowed me that voice. I have the right to say to a director, 'That's not good enough'.
"A lack of money will affect the script. They will tell the writer, 'this is the budget we've got. Don't write something that's going to cost us more.'"
Hercule Poirot appeared in 33 novels and 51 short stories by the late Christie, from 1920 to 1975, and David has starred in the glamorous television adaptations since 1989.
He revealed: "The word is, unofficially, some scripts may be in development. Once the script is developed, ITV has to say, 'Have we the money to make it?'
"I'd like to think that over the next 18 months we could do six films and then I think he should hang up his spats. When he does I'll have two reactions. Thrilled to have achieved that - a complete works of such an iconic literary figure. Then devastated, as it will be a death."