By Agence France-Presse
The aircraft was flying from Herat to the neighbouring province of Farah on Friday night when it experienced "technical problems", Farah provincial governor spokesman Nasir Mehri told AFP.
Farah police spokesman Mohibullah Mohib confirmed the death toll. The defence ministry said five people were killed.
A technical team has been sent to the area to investigate the accident the defence ministry said in a statement.
But in a WhatsApp message to journalists, Taliban spokesman Zabihullah Mujahid said militants had shot down the "enemy helicopter".
The Taliban has stepped up attacks on security forces as Afghan and international players ratchet up efforts to convince the group to engage in peace talks to end the 17-year war.
US officials met with Taliban representatives in Qatar in July, and another meeting could be held this month.