Brett Stibners top-scored for Australia with 21 points while Mohammad Hassan Sayari scored 22 points for Iran.
Iran will play holder USA on Friday in Group B.
The competition began on August 25 and will continue until September 5 at two venues in Tokyo: Musashino Forest Sports Plaza for the group matches and Ariake Arena for the finals.
Germany, Algeria, Britain and USA are also in Group B. The top four of the six teams in each group go through to quarters.