In a statement on Wednesday the Lebanese Shia Muslim group said this act "has done very great harm to Islam and Muslims by this group that claims affiliation to the religion of mercy, compassion and humane principles".
An Islamist website on Tuesday carried a video clip of the execution of the man who identified himself as Nick Berg, with a statement saying a group linked to al-Qaida did it in revenge for the abuse of Iraqis by US troops.
Hizb Allah said Berg's killing had diverted the world's gaze from an escalating furore over the abuse of Iraqi prisoners by occupation soldiers.
"The timing of this act... is suspect timing that aims to serve the American administration and occupation forces in Iraq"
Hizb Allah statement
"The timing of this act that overshadowed the scandal over the abuse of Iraqi prisoners in occupation forces prisons is suspect timing that aims to serve the American administration and occupation forces in Iraq and present excuses and pretexts for their inhumane practices against Iraqi detainees."
The influential Lebanese Islamist group, which the United States deems "terrorist", said the executors' behaviour was closer to "the Pentagon school - the school of killing and occupation and crimes and torture and immoral practices that were exposed by the great scandal in occupation prisons".
Hizb Allah forced Israeli troops to withdraw from south Lebanon in 2000 after a 22-year occupation, and US Marines to evacuate the country after 1980s bombings against its embassy and barracks.