"An improvised explosive device was found at his home and the man admitted that he wanted to use it to target a swingers' club," the source told AFP.
The plot is the fifth to be thwarted in France this year and comes with the country still on high alert after a string of jihadist assaults since 2015 that have claimed more than 240 lives.
It was revealed just hours after police sources said two men had been charged on suspicion of planning an attack in the name of the Islamic State group which may have targeted gay people.
Sources close to the probe said the men, described as friends aged 21 and 22, were arrested Saturday in the Seine-et-Marne region east of Paris.
Searches found two knives, a detonation system and IS propaganda material in their possession, a source said.
"Their plan was still ill-defined at this stage, but there were elements to suggest they planned to attack homosexuals," one source added.
The two men, said to be unknown to security services, were charged on Tuesday by an anti-terrorism judge and detained.
Agents with the DGSI domestic intelligence service were first alerted to their plans several weeks ago after "they referred several times to a plan for an attack," said a source close to the inquiry, describing them as "very determined".
"One of them had mentioned trying to find a weapon," another source told AFP.
Prime Minister Edouard Philippe told parliament in March that a total of 51 planned attacks had been thwarted since January 2015, when gunman killed 12 people after storming the offices of satirical magazine Charlie Hebdo.
(This story has not been edited by Business Standard staff and is auto-generated from a syndicated feed.)