The tiny cub, weighing just a few kilos, was found on Wednesday inside a pet's travel cage in a garage to the city's north. She is believed to be between one and two months old, Bruno Hamon, deputy chief of Marseille's customs office, told AFP.
A garage employee, who was temporarily detained by customs agents, said only that he had taken the cub from a Marseille building after its former owners said they were overwhelmed by the situation.
The animal was handed to the SPA animal protection charity who have passed her on to a specialist NGO which works to shelter wild animals, customs officials said in a statement.
The discovery came just a day after French police seized a six-week-old lion cub from an apartment in the Paris suburb of Valenton on Tuesday, arresting its owner, a 30-year-old man known to police.
The female cub was discovered in a child's bed and was in good health. A source close to the investigation said the cub was likely stolen and that the suspect appeared to have intended to resell her.
Police had been alerted to the cub by videos circulating on social media, in which a man offered her for sale for about 10,000 euros ($11,470). There have been a string of such cases around France in recent years,
including a half-starved cub rescued from an apartment in Noisy-le-Sec, east of Paris, last year.
A small abandoned cub was also found in a cage in a field outside the Dutch city of Utrecht earlier this month.