David Koubbi, who is acting for the writer Tristane Banon, spoke on Tuesday to newspaper 20 Minutes and said his client is determined to bring him to justice.
He claimed to be "exasperated" by rumours earlier this week that the French charges against him would be dismissed.
"The prosecutor has denied this. The investigation is continuing," he said. "The DSK affair in France is only just beginning."
Commenting on Strauss Kahn's liberation in New York, the lawyer complained of "crass indecency" on the part of the former IMF chief's friends in France. He said they were engaged in a display of "self-congratulation."
"I regret this outcome. I regret it for Nafissatou Diallo because I believed her," he said.
Tristane Banon alleges that the former IMF chief sexually assaulted her in 2003, describing him as a "rutting chimpanzee." Her story was given a further twist when it emerged her mother, Anne Mansouret, had herself had a brief sexual liaison with Strauss-Kahn.
On Tuesday, Mansouret took to the airwaves to express her indignation about Strauss-Kahn's release and the reaction of many Socialist officials.
"I'm angry morning, noon and night," she said on BFMTV. "There is no reason to consider Mr Strauss-Kahn as innocent. What repulses me is the reaction of Socialist MPs. They are all repeating that Dominique Strauss-Kahn is innocent when that's not the case."
Koubbi said his client was disappointed about what had happened to Diallo but she was not discouraged.
"She's in a combative mood. She is not prepared to let this drop," he said. "Tristane Banon wants justice to be done."