Hailemariam, speaking at a summit of the 54-member organization, charged that of those indicted by the ICC, "99 percent are Africans," the BBC reported Monday.
He said, "Something is flawed" within the ICC because "the process has degenerated into some kind of race hunting."
Hailemariam accused the ICC of "chasing" Kenyan President Uhuru Kenyatta and his deputy, William Ruto, in connection with violence after elections in 2007 in which 1,000 people were killed and 600,000 forced to flee their homes.
Kenyatta is to go on trial before the ICC in July. Ruto's trial was to begin this month but has been postponed, with a new trial date yet to be set.
The Ethiopian prime minister said Kenyatta and Ruto should be tried in African courts.
The AU assembly has mandated the African Union "to take care of this issue, to present to the U.N. the core of this matter," he added.
The ICC says it acts impartially.
Wilfred Nderitu, a Kenyan lawyer representing about 150 victims of the 2007 violence, said he feared for the safety of the witnesses if Kenyatta and Ruto were tried in African courts.