Chief Cabinet Secretary Shinzo Abe made the announcement about the missiles as South Korean officials warned of the possibility of more launches, without giving details or a timeline.
Abe said he said he couldn't rule out the possibility that a long-range missile could be test-fired at a later point. But he said, "They are not prepared to launch another one right now."
North Korea test-fired seven missiles on Wednesday, triggering international condemnation. One of the missiles was believed to be the Taepodong-2, which experts fear could reach parts of the United States.
Abe demanded the North quickly return to the multilateral talks on its nuclear weapons program, which have stalled as the North expressed anger at financial sanctions imposed by the United States. The missile crashed shortly after takeoff.
He also called on the U.N. Security Council for tough action. Japan called on the council to slap economic sanctions on North Korea in an emergency session that started Wednesday, but faced opposition from Russia and China, who insisted diplomacy was the only way to resolve the crisis.
South Korean media reported Thursday that Pyongyang has more missiles on launch pads and ready for firing, but they were believed to be either short- or medium-range.
Japan believed the tests were aimed at winning chances for bilateral talks with Washington, he added.
Former Deputy Secretary of State Richard Armitage, who was in Tokyo at a privately sponsored conference also attended by Abe, said the North had taken advantage of Washington's lack of proper attention to Northeast Asia.