Unification Ministry spokesman Lim Byeong-cheol told a press briefing that the government will sternly deal with North Korean provocations, while continuing to monitor changes in Pyongyang's attitude and situations.
Lim, however, said Seoul will maintain its position that it will seek to build trust through cooperation and dialogue with North Korea.
His comments came after North Korea on Sunday fired short-range projectiles, presumed to be tactical missiles, into the eastern waters.
It marked North Korea's second missile launch in 2015.
Meanwhile, Lim said it would be hard for the family reunion event to be held in the Lunar New Year holiday that falls in February.
South Korea offered to hold talks with North Korea in January to discuss issues of mutual concern, including the reunion of Korean families separated by the 1950-53 Korean War, but Pyongyang has not responded yet.