Mr Macron’s controversial texts are expected to be published before the end of this week, and passed before the end of September.
Mr Mélenchon, the head of the hard-left France Unbowed political party and a member of parliament, urged people during a rally in the southern port town of Marseille to “descend on Paris” on September 23 to protest against the labour reforms he said amounted to a “social coup d’état”.
The left-winger said: “The French must take to the streets of Paris en masse to protest against the government’s undemocratic labour reforms, against what is essentially a social coup d’état.”
The firebrand told a crowd of cheering supporters it was time to move from “words to action”.
He said: “People must stand up and fight back! It is our duty to say that we will not give up… The people’s inertia is a tyrant’s best defence.”
The left-wing leader added that Mr Macron had not won power on his own merit.
The president, he argued, was elected to power because of his promise of a break from traditional left-right politics, and because he was seen as the lesser of two evils after right-wing chief Marine Le Pen made it to the second round of voting.
He said: “The French do not want him (Mr Macron) to assume full executive powers.
“They got rid of the politicians they did not want: they got rid of Nicolas Sarkozy’s party, they got rid of François Hollande’s party, and then they got rid of the Front National. Mr Macron was the last man standing.”
The president’s labour market reforms, Mr Mélenchon added, are a “grave error of judgment”.
He said: “Mr Macron was wrong. The French do not want liberal policies that will inevitably lead to brutal competition and pit workers against each other.”
The hard-line leftist added that he was “shocked” by the president’s claim that France was “unreformable” because the French “hate reform”.
The French do not hate reform per se, but are united in rejecting the ones put forward by Mr Macron’s government, Mr Mélenchon said.