Several hundred sex workers and gay-rights activists marched to the scene of the murder of Vanesa Campos, a Peruvian-origin transsexual, on Friday.
She was killed in the Bois de Boulogne, the park on the edge of the city where many sex workers operate, including transsexuals, many of whom come from Latin America.
Campos was killed by a group of men on the night of 16 August as she tried to stop them robbing a client.
Such groups attack and rob prostitutes and their clients.
Activists say the number of such crimes has increased over the last three years.
Friend of Campos say that the victim was "a leader in the fight" against the thieves.
The march's organisers demanded the repeal of the 2016 law, which decriminalised prostitution but imposed fines on clients of up to 1,500 euros and 3,750 euros for repeat offenders.
They claim it reduced prostitutes' takings and forced them to operate in out-of-the-way places, where they are vulnerable to attack.
They also complained that no government ministers have condemned the killing, in particular targeting Equality Minister Marlène Schiappa.
"We have the impression that our lives don't matter," Thierry Schaffhauser of the sex-workers' union, Strass, told the AFP news agency. "If it had been a gay in the Marais [the centre of gay life in the centre of Paris] who had been attacked, there would have been a reaction."
Not all activists agree with the call to repeal the law.
"Prostitution is rape and slavery," a statement from the Mouvement du Nid campaign said. "Denying that facilitates the offence and trivialises Vanesa's murder and all the others."