According to a source close to the investigation, Depardieu is friends with the young woman's father and had "taken her under his wing", giving her tips on how to start her acting career.
She studied in a school where he gave lessons. According to her agent, the actress has been "destroyed" by the affair.
She reportedly alleged that he abused her during an "informal rehearsal" for a play. She declined to comment to French media.
Temime said Depardieu was "totally thunderstruck by this complaint". "He totally denies any attack. Gerard Depardieu is distraught. This accusation goes against everything he respects," he said.
Temime added: "I regret the public nature of this procedure, which is highly detrimental to Gerard Depardieu, whose innocence I am convinced will be recognised." Depardieu is arguably France's most famous actor.
One of his most famous co-stars, Catherine Deneuve, sparked controversy this year when she led a pushback against the #MeToo movement that was set in motion by allegations of sexual abuse against American movie mogul Harvey Weinstein and exposed industry-wide abuse.
Deneuve was the most high-profile of 100 French women who signed an open letter criticising the movement and the drive to expose sexual harassment in France and around the world. They said the freedom of men to pester women was "essential to sexual freedom" and that the campaigns had unleashed a torrent of "hatred against men and sex".
They claimed "puritanism" was running rampant "like in the good old days of witchcraft".
The letter sparked debate and some anger in France. However, one of the signatories, radio host and former pornographic film actress Brigitte Lahaie, caused outrage when a few days later she suggested rape victims feel pleasure.
Deneuve slammed the rape comment as "worse than spitting in the face of all those who suffered from this crime". Lahaie apologised and wept in a television interview, saying her words had been "taken out of context".
The claims against Depardieu have him back in the headlines for reasons other than his acting.
In recent years he has been in the news for attacking French tax laws, moving to Belgium in protest and later developing close ties to Vladimir Putin's Russia. He was also known for his drunken escapades, which include urinating in the aisle of an Air France plane bound for Dublin as it prepared to take-off, forcing the aircraft to turn back. He claimed to drink up to 14 bottles of wine a day but then in 2016 said he had given up drinking because "I really no longer like drunkenness".
He has appeared in 200 films over six decades and holds a rare position as a French actor who is known in Hollywood.
He won a Golden Globe for his performance in Green Card, a 1990 English-language romantic comedy co-starring Andie MacDowell.
His first big hit in France was Les Valseuses, (Going Places), Bertrand Blier's classic farce about two wandering thugs.
Before he crossed the Atlantic to play a bon vivant Frenchman to MacDowell's prissy horticulturist, Depardieu played roles from Jean Valjean, the thief-turned-saint in Les Miserables, to Christopher Columbus.
In 2014, he had the leading role in Welcome to New York, a film inspired by from the life of Dominique Strauss-Kahn, the former director of the International Monetary Fund who was accused in 2011 of sexually assaulting a hotel maid.
