Japan has been reluctant to join the United States, its most important ally, in its efforts to set up the coalition because of its close economic ties with Iran, a major supplier of oil.
Citing unidentified government sources, the Yomiuri said Japan was considering a plan to send its Maritime Self-Defense Force (SDF) on information-gathering missions in the areas around the Strait of Hormuz and Bab al-Mandab shipping lane between Yemen, Djibouti and Eritrea.
It would also consider including the Strait of Hormuz in the SDF's sphere of activity if Iran agrees, the paper said.
Iran has denounced U.S. efforts to set up the coalition and says countries in the region can protect waterways and work towards signing a non-aggression pact.
The Japanese government is set to make a final decision, including whether the plan is feasible, after the United Nations General Assembly later this month, the Yomiuri said.
Global commodity trading has been rocked in recent months by the seizure of a British tanker and a series of attacks on international merchant vessels that the U.S. and Britain have blamed on Iran. Tehran denies involvement.Britain last month became the first U.S. ally to announce its participation, although most European countries have been reluctant to sign up for fear of adding to tension in the region.