"We know the circumstances: He was taken during a clash between Colombian troops and the FARC. The confrontation was brutal, there were deaths, and the journalist was taken prisoner," Juppe told reporters at a political rally.
Juppe said he had no further information for the moment, but said that the French foreign ministry hostage crisis cell had been activated.
Earlier, officials said that French television reporter Romeo Langlois went missing on Saturday when he was with a military and police patrol in Caqueta province ambushed by the Revolutionary Armed Forces of Colombia (FARC).
Three soldiers and one police officer were killed in the attack and five others remain missing, Colombian military officials said.
"The French journalist was accompanying the army unit in the course of an anti-drug operation when the unit came under attack from FARC forces," said a French embassy official, who spoke on condition of anonymity.
Colombian authorities have launched a search operation.
Global television network France 24 said that Langlois had been on assignment for them, reporting alongside Colombian forces carrying out anti-narcotic operations in the south of the country.
"We know that it's a dangerous region. Of course we are worried, but we have confidence in Romeo who knows the region well and is very experienced. We hope therefore that he is safe and well," said editorial director Nahida Nakad.
The FARC has been at war with the Colombian government since 1964 and is believed to have some 9,000 fighters in mountainous and jungle areas, according to government estimates.
Their deadliest attack this year was committed last month when the rebels killed 11 soldiers in the town of Arauquita, near the border with Venezuela.
Earlier this month, the FARC released the last 10 police officers and soldiers they were holding hostage.
But Olga Gomez, president of the Free Country Foundation, estimates the FARC is holding more than 400 civilians hostage. The FARC says the foundation's numbers are false and biased, but has released no figures of its own.
The last French national held by the FARC was Ingrid Betancourt, a former Colombian senator and presidential candidate. She was abducted during her presidential campaign in February 2002, along with her assistant, Clara Rojas.
Betancourt and 14 other hostages - including three US military contractors - were freed in an operation by the Colombian military on July 2, 2008.