Tokyo said China was acting "unilaterally and without compromise", as it also highlighted concern about North Korea's nuclear programme and Russian moves in violence-wracked Ukraine.
The white paper accused Beijing of "raising concerns among the international community" as it ramped up criticism from last year's report, an annual summary of Japan's official view on defence matters.
"China, particularly over maritime issues, continues to act in an assertive manner, including coercive attempts at changing the status quo, and is poised to fulfil its unilateral demands without compromise," said the report entitled "Defense of Japan 2015".
It is also embroiled in a separate row with Japan over the Tokyo-controlled Senkaku islands -- which it calls the Diaoyus -- in the East China Sea, as Chinese ships and aircraft regularly test Japanese forces in the area.
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While the Sino-Japanese spat has cooled considerably over the last 12 months or so, observers have warned that it could spiral into a limited armed conflict.
Separately, Japan has complained that China may have started offshore drilling for gas in the disputed waters.
The document repeated Tokyo's concerns over China's growing assertiveness and widening naval reach in the Pacific and over what it calls the "opaqueness" of Beijing's sky-rocketing military budget.
But it also noted that China has worked to set up an emergency hotline with Tokyo to prevent unintended conflicts at sea.
Following the issuing of the Japanese white paper, Beijing criticised the document for playing up "the so-called 'China military threat'".
Chinese state news agency Xinhua said that a foreign ministry spokesman argued the white paper "ignores facts, makes irresponsible remarks... Deliberately plays up the 'China threat' and stirs up tensions".