"In a statement read for him in the Bosnian town, the US president admitted the failure of the international community to protect the enclave, and said those responsible must be pursued.
More than 7,000 Muslim men and boys were killed by Bosnian Serb troops.
The massacre was the worst atrocity in Europe since the Second World War.
Hundreds of victims of the massacre were buried at a ceremony outside the town on Sunday.
European leaders and the presidents of all former Yugoslav republics who had gathered for the ceremony heard Mr Obama's words that "there can be no lasting peace without justice".
Mr Obama urged "the prosecution and arrest of those that carried out the genocide", and added: "This includes Ratko Mladic who presided over the killings and remains at large."
"I would have preferred that all of us have been killed together, then we would not have had to live through this," Hasan told the AFP news agency."
Noticia da BBC.