Macron's comments, made during a visit to Paris of DR Congo President Felix Tshisekedi, currently head of the African Union, came after a woman was killed by demonstrators in the Chadian capital as crowds protested against the newly installed junta, despite the military's ban on such gatherings.
"We want to express our concern about developments, and condemn with the greatest firmness the repression of demonstrations and the violence that took place this morning in N'Djamena," Macron told reporters at the Elysee Palace.
The Sahel country's new military junta on Monday appointed a transitional prime minister, who called for a nationwide effort to speed the return to civilian rule, suspended after the shock battlefield death last week of veteran leader Idriss Deby Itno.
The so-called Transitional Military Council (TMC) led by Deby's 37-year-old son Mahamat named Albert Pahimi Padacke, a distant runner-up in the April 11 presidential vote, as prime minister.
Macron called on the council to honour its commitment to "a peaceful and politically inclusive transition", warning that France, the former colonial power in Chad, was opposed to any attempt to simply designate Deby's successor.
"I am not in favour of a planned succession," he said.