German reporter Ann-Kathrin Stracke says the former leader touched her buttocks repeatedly during a 2018 interview.
Ms Stracke said the global MeToo movement, which has highlighted sexual harassment and assault against women, inspired her to come forward.
The 94-year-old has denied the charge.
An emailed statement from Mr Giscard d'Estaing's lawyer reported in the New York Times said he did not remember the incident, was not aware of any complaint, and that he was considering legal action after the "particularly undignified and offensive media attack".
Ms Stracke filed a report in France about the incident in March. The German reporter told news agency AFP she decided to tell her story because "I think that people should know that a former French president harassed me sexually".
She has also said the MeToo movement "showed me how important it is to talk about these matters in the open".
More about: France