Today's statement was Pyongyang's first reaction to Seoul's announcement last week that the 12 restaurant staff and their manager had been released from government custody.
The group had been "released into society", the South's unification ministry said, after the intelligence service had completed investigations into their case.
North Korea claims the group was kidnapped.
A spokesman for its emergency committee set up for "rescuing" abductees described the ministry's announcement as a "mean plot" aimed at "covering up the truth behind the group abduction".
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"We will continue fighting until we can rescue and bring back our female citizens," the spokesman added in a statement carried by the North's official KCNA news agency.
The waitresses had been working at a North Korea-themed restaurant in China. They made headlines when they arrived in the South in April as the largest group defection for years.
While Seoul said they fled voluntarily, Pyongyang claimed they were kidnapped by South Korea's National Intelligence Service and waged a vocal campaign through its state media for their return.
Nearly 30,000 North Koreans have fled poverty and repression at home to settle in the capitalist South.
But group defections are rare, especially by staff who work in the North Korea-themed restaurants overseas and who are handpicked from families considered "loyal" to the regime.
In another high-profile case, the South said last week that North Korea's deputy ambassador to Britain and his family had defected to Seoul.
It said Thae Yong-Ho was driven by his disgust for the Pyongyang regime, admiration for South Korea's free and democratic system and concerns for his family's future.
It said the South had brought the "fugitive" to Seoul to use him in its anti-Pyongyang smear campaign.
Thae was believed to have worked at the embassy in London for 10 years.