Syed Noor, who has directed and produced several hit films, said Sharmeen stole the central idea, script and name from a film he made about two years ago.
Sharmeen's "A Girl in the River: The Price of Forgiveness", about a survivor of an attempted honour killing in her country, has won the best documentary short award at the 88th Academy Awards.
This is the second win for Sharmeen, who previously bagged the Oscar in the same category in 2011 for "Saving Face".
"I am really disheartened that she copied things from my film but didn't bother to give me any credit," he said.
Noor said he was disheartened that the idea and the name was copied from his film but he was not given due credit, but he would not pursue legal action against Sharmeen.