The resolution of condemnation was approved by 183 of the 185 legislators present two days after North Korea's third nuclear test, Yonhap News Agency reported.
"We cannot tolerate North Korea's nuclear test and strongly condemn it as a serious provocation threatening the lives and safety of the South Korean people," the resolution stated. "Responsibility for all issues arising from [the nuclear test] lies with North Korea."
Seoul's nuclear safety commission said Thursday it has not yet detected any change in the levels of radiation or nuclear substances at any of its 122 monitoring stations that might further confirm the test.
Detection of certain isotopes in the atmosphere can help determine whether the test used a plutonium- or uranium-based device. Such materials could take several days to travel to the south.
The commission has increased the frequency of monitoring, reducing its automatic detection cycle from every 15 minutes to every five minutes.