China has been embroiled in territorial disputes with smaller neighbors including Vietnam and the Philippines over islands, reefs and lagoons in the South China Sea.
The Iranian minister's visit follows a trip to close ally Russia and comes just after the first-ever drills among the navies of the three countries in the northern part of the Indian Ocean.
Japan is buying expensive American F-35 stealth fighters capable of short takeoff and vertical landing and converting a pair of helicopter carriers for them.
China has expressed anger over new U.S. arms sales to the self-governing island democracy of Taiwan and the passage last week of an American warship through the Taiwan Strait.