Strauss-Kahn was charged earlier this year with "aggravated pimping" for allegedly aiding and abetting the prostitution of seven women - a charge punishable by up to 10 years in prison.
His acquittal, along with nearly all the other defendants in the case, did not come as a surprise.
But further charges could be brought against the former IMF boss, according to Marie Alibert, spokesperson for the feminist group Osez le feminisme.
"What we can say is that one of the prostitutes, in her account of the event, during the trial, mentioned was is very clearly a rape scene and she gave graphic, horrible details about it," she told RFI. "So this we hope could lead to further charges against Dominique Strauss-Kahn.
"He is a very powerful man, he's been involved in several ambiguous situations and he's been accused in several occasions. We have the feeling that the noose is tightening against him now, because every time he managed to escape the charges and to be found not guilty but we do hope now something will happen."
Also on Friday a second bill to protect prostitutes passed in the lower house of the French parliament.
Anyone caught using a prostitute's services for cash is liable to a 1,500-euro fine.
Even if the Strauss-Kahn case brought attention to the problem, Grégoire Théry, secretary general of prostitutes' rights group the Mouvement du Nid, says the verdict is still disappointing.
"On one hand, the trial has helped raise awareness on the realities of all forms of prostitution," he said on Friday. "But, on the other hand, the verdict is very disappointing for the victims because it's very strange to note that we have heard and understood that there are victims, everybody in France understood that but in the end there will be no perpetrators. It's a crime with victims but no perpetrators somehow".
Supporters of the new prostitution bill argue it will help tackle human trafficking networks and pimps.
Critics say that criminalising prostitution will push the issue further underground.