Mozambique’s Defence Minister Jaime Neto has said that a video showing people dressed in army uniforms beating and killing a naked woman was doctored.
The culprits had been identified and would be punished, he added.
The video caused outrage after it was circulated on social media.
The defence ministry promised to investigate.
The video was said to have been filmed in the gas-rich Cabo Delgado province, where government troops are battling militant Islamists.
The militants are known as al-Shabab, and have pledged allegiance to the Islamic State militant group.
They have carried out a series of attacks on villages and towns in the area over the past three years, leaving more than 1,500 people dead and at least 250,000 homeless.