"According to my information, Arutyunyan did not belong to any foreign terrorist formation. He was not affiliated with political parties either," Vano Merabishvili said.
Merabishvili said Arutyunyan prepared the attack on the U.S. president on his own and collected all the material he used without any help from any terrorist organizations.
The minister said Arutyunyan's trial would start at the end of November this year.
Arutyunyan, 27, was arrested in Tbilisi on July 20 after a shootout with Georgian police that resulted in the death of Col. Zurab Kvlividze, the head of the Georgian Interior Ministry's counterintelligence department.
Arutyunyan is accused of throwing a hand grenade at U.S. President George W. Bush and Georgian President Mikhail Saakashvili while they were addressing a public audience on Freedom Square in central Tbilisi.