"The North this morning notified us that it will only allow returning trips from Kaesong and will ban trips to the complex," Unification Ministry spokesman Kim Hyung-Suk told reporters.
Kim said the North had not specified how long the ban would remain in effect.
Describing the North's move as "very regrettable", Kim said his government's first priority was the safety of the estimated 861 of its citizens currently in Kaesong.
"We expect our people currently in the North to return safely," he said.
The industrial complex, which lies 10 kilometres (six miles) inside North Korea, was established in 2004 as a symbol of cross-border cooperation.
North Korea has always been wary of allowing crises in inter-Korean relations to affect the zone -- a crucial hard-currency earner for the communist state.