North Korea launched at least two unidentified projectiles into the sea on Friday according to South Korea's military.
Pyongyang called South Korea's president "impudent" and added that inter-Korean talks were over.
The development comes in the light of the North's protest against joint military drills conducted by South Korea and the United States, which kicked off last week.
Pyongyang has described the exercises as a rehearsal for war.
The North has fired several projectiles into the sea in recent weeks however Japan's defence ministry said it did not see any imminent security threat from the latest launch.
The "unidentified projectiles" were launched shortly after 8 a.m. Friday (2300 GMT Thursday) and flew around 230 km (142 miles) to an altitude of 30 km (18 miles), according to South Korean military officials.
North Korea declares talks "over"
The launches have complicated attempts to restart talks between US and North Korean negotiators over the future of Pyongyang's nuclear weapons and ballistic missile programmes.
Those denuclearisation talks have been stalled despite a commitment to revive them made at a June 30 meeting between US President Donald Trump and North Korean leader Kim Jong Un.
The loss of dialogue momentum between the North and South and the stalemate in implementing pledges made at a historic summit between their two leaders last year was entirely the responsibility of the South, a North Korean spokesman said.
"We have nothing to talk any more with the South Korean authorities nor have any idea to sit with them again," said North's spokesman for the Committee for the Peaceful Reunification of the Country in a statement carried by the official KCNA news agency.
US President Donald Trump and Kim Jong Un have met twice since their first summit in Singapore last year and said their countries would continue talks.
However, little progress has been made on the North's denuclearisation programme.