Former United States prisoners of war captured by the Japanese will also attend the event, the Yomiuri Shimbun said, with US officials hoping their presence will remove any impression it is an apology.
Obama will offer a floral tribute and make comments in front of a cenotaph for atomic bomb victims on Friday, becoming the first sitting US president to visit the city.
Earlier this week, he told Japanese television he will not say sorry for the bombing.
Tens of thousands were killed by the fireball that the powerful nuclear blast generated, with many more succumbing to injuries or illnesses caused by radiation in the weeks, months and years afterwards.
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The southern city of Nagasaki was hit by a second bomb three days later, killing 74,000 people, in one of the final acts of World War II.
The speed, circumstances and repercussions of then US president Harry Truman's decision remain contentious. In Japan, perhaps a majority believe the mass bombing of civilians was unnecessary and may even have been a crime.
Yesterday, Hiroshima mayor Kazumi Matsui met with Abe and demanded that Obama meet with atomic bomb victims, newspaper reports said.
"If victims and the president meet face to face, he may be able to understand the feelings of the victims," Matsui told reporters after his meeting with Abe, the Yomiuri reported.
Obama is due to arrive in Japan later today for a meeting of the Group of Seven industrial powers, which begins tomorrow.
Obama will likely have a bilateral meeting with Japanese Prime Minister Shinzo Abe late today, top government spokesman Yoshihide Suga said.