Cameron questioned why the plot focused more on Thatcher's battle with ill health in her later years, including her struggle with dementia, instead of her time in office as the U.K.'s first female prime minister.
He told BBC Radio 4, "It's a fantastic piece of acting by Meryl Streep. You can't help wondering, why do we have to have this film right now? It is a film much more about aging and elements of dementia rather than about an amazing prime minister... (It's) a film I wish they could have made another day."
However, Streep, who has been nominated for a Golden Globe for her role as Thatcher in the drama, feels Cameron's remarks were inappropriate.
She tells the Sunday Mirror, "What about him (Cameron) saying on the radio that people should wait until she is dead (to make the film)? How must that make her feel?
"If I'd made a film about Margaret Thatcher and she had something wrong with her lungs no one would have raised a hue and cry. But it's because it is mental frailty she is afflicted with that is what terrifies us most."