Tenketsu Harimoto and Yuki Kawamura combined for 42 points to spark Japan, which fended off Bahrain's spirited comeback in a FIBA World Cup qualifier.
France outscored Japan 19-9 in the pivotal fourth quarter, including a 17-2 run that defined the overall play in the final period.
The hosts pulled away over the final 20 minutes in Okinawa, outscoring the Central Asian national squad by 25 points in that span.
Veteran guard Yudai Baba scored a team-high 27 points in Tehran, but Iran outscored Japan 19-5 in the tone-setting second quarter.