The French Foreign Ministry summoned Iran's charge d'affaires in Paris on Saturday over the execution of a British-Iranian national accused of spying, the ministry said in a statement, expressing its indignation about the case.
Iran's judiciary said earlier in the day that Alireza Akbari, a British-Iranian national who once served as Tehran's deputy defence minister, had been executed, defying calls from London for his release.
"He was also warned that Iran's repeated violations of international law cannot go unanswered, particularly with regard to the treatment of foreign nationals whom it arbitrarily detains," the French Foreign Ministry said.
Like other Western powers, France has sought to increase pressure on Tehran in recent months and President Emmanuel Macron has criticised the crackdown by authorities on protesters and expressed support for women fighting for more rights.
Macron called the unrest in the country a "revolution".
"Something unprecedented is happening," Macron said in an interview in November. "The grandchildren of the revolution are carrying out a revolution and are devouring it," Macron said when asked to qualify what was taking place in Iran.
France last year said a total of seven French citizens were being held in Iran in what Paris has called arbitrary detention - a further sign of deteriorating relations between the two countries.
France lashed out at Iran on Oct 6, accusing it of "dictatorial practices" and taking its citizens hostage after a video was aired in which a French couple appeared to confess to spying.