"It is a serious act of provocation against the security of neighbouring countries, including our country," Chief Cabinet Secretary Takeo Kawamura was quoted by Jiji Press as saying.
The government's top spokesman also said the act was against a UN Security Council resolution, according to Jiji.
North Korea today test-fired two more missiles, the South Korean defence ministry said, further stoking tensions sparked by its nuclear standoff with the international community.
Pyongyang has warned Japan to stay clear of some areas off its east and west coasts during military exercises lasting until July 11.
Published 04 July 2009, 05:06 IST