Presiding judge Tomas Kubec ruled that Randy Blythe's actions did not constitute the crime of causing an injury leading to death.
"We did not find criminal responsibility in the actions of the defendant," he said. "We found moral responsibility. There has been the death of a young man who had not been guilty of anything."
Kubec said the concert promoters were ultimately to blame for failing to prevent fans from clambering onto the stage.
"We reached the conclusion that there was a serious fault on the side of the promoter and organiser of the concert."
Prosecutors immediately appealed against the acquittal, meaning that the case will be reviewed by the Czech High Court.
More top news
Scotland finally injected some momentum into their World Cup preparations as they beat Italy 48-7 triumph at Murrayfield.
Labour leadership candidate says Britain playing its role in the migrant crisis would help Cameron secure the promised reforms in Brussels.
Ten people have been taken to hospital and another two treated for injuries after a bus crashed into a tree in east London.