"Neither the judicial enquiry nor the hearing have established that Mr Strauss-Kahn is guilty" of procuring prostitutes for sex parties he attended in Paris, Brussels and Washington, said prosecutor Frederic Fevre.
The 65-year-old who was once tipped for the French presidency has denied knowing the women at the orgies were prostitutes, or that he organised for them to be there, which could have landed him in jail for up to 10 years for pimping.
Strauss-Kahn sat with his arms crossed as Fevre called for the court to find him not guilty.
The prosecutor argued that the economist's notoriety "should not be a presumption of guilt".
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"Our legal system must take pride in never convicting someone if there is any doubt. I therefore request his acquittal, pure and simple," said Fevre.
In another boost for Strauss-Kahn, two ex-prostitutes who attended the orgies dropped a civil lawsuit against him, with lawyers saying they lacked enough proof to win the case.
He was charged with pimping shortly after the New York scandal when his name cropped up in a probe into a prostitution ring in northern France, which provided sex workers for orgies he attended.
Strauss-Kahn found himself in the dock alongside a colourful cast of characters including a senior police officer and brothel owner Dominique Alderweireld who is known as "Dodo the Pimp"
"He was the boss," Fevre said of Alderweireld who is accused of sending prostitutes from Belgium to the parties just over the border.
Fevre requested a sentence of one year in jail and a fine of 10,000 euros (USD 11,000) against him.
Dodo separately provided prostitutes to friends of Strauss-Kahn who brought them to the sex parties. The two businessmen maintain they kept it secret from him that the women were paid.