Calling the incident "a grave provocation," the North Korean Red Cross also warned of "unthinkable consequences" if Seoul doesn't repatriate the defectors, Yonhap reported.
"This event, a fabrication of the South Korean puppet regime, is a grave provocation against [North Korea], an intolerable insult that cannot be allowed," a North Korean Red Cross spokesman said in statement, according to North Korean media outlet Uriminzokkiri.
This is the first public statement North Korea has issued since 13 North Koreans -- a man and 12 women --arrived in the South last Thursday, after they sought asylum at Seoul's embassy in Bangkok.
North Korea slammed Seoul, claiming South Korea "dragged" the North Koreans to a "Southeast Asian country."
South Korean Foreign Minister Yun Byung-se said the group defection should serve as a sign to the North.
"If the North Korean government continues to make the wrong choices that include nuclear weapons development, similar incidents will continue to arise," Yun told reporters in Seoul, adding the "winds of change" are sweeping across Asia and around the world.
"I believe the North Korean restaurant workers came to the South, to find new freedoms," Yun said.
The number of North Koreans defecting to the South has slightly declined since Kim Jong Un fully assumed power in 2012, but in the first quarter of 2016, that number was up from the same time period in 2015.
A total of 342 North Koreans defected to the South January-March 2016, 51 more people than in 2015.
A significant majority of defectors are women, but the number of male defectors was up in early 2016 – 77 of the 342 defectors were men, up 22 from the first quarter of 2015.