The Printemps Haussman store was evacuated and cordoned off after police found and disposed of the explosives, police said.
Earlier, the French news agency AFP received a letter signed by a group calling itself the Afghan Revolutionary Front warning of "several bombs" placed in the store.
"If you don't intervene before Wednesday 17 December, they will explode," warned the statement.
However, the explosives, found in the toilets on the third floor of the store, had no detonators.
"As far as we understand, this was not a set-up that was designed to explode. We will lead the inquiry and find the authors," said interior minister Michèle Alliot-Marie.
The mysterious Afghan group called for the withdrawal of French troops from Afghanistan by the end of February.