At least 20 members of the security forces are believed to be killed or wounded when the fighters attacked the Anar Dara district's police and administrative offices on Monday morning.
Bakhtawer added that casualty figures were uncertain because intense fighting was continuing at and near the site.
No group immediately claimed responsibility for the attack but both the Taliban and the Daesh group are active in eastern Afghanistan, particularly in Nangarhar province.
"We sent more troops to the district and also called in air power to take part in ongoing fighting to halt the Taleban's progress", Mr Mehri said.
The largest number of militants (54) was killed in the southern province of Kandahar.
The insurgents have recently stepped up attacks against Afghan security forces across Farah province.More news: Meghan Markle in J Crew coat for Birmingham away day
Four days earlier, Taliban attacks on police checkpoints killed eight police officers.
United States and Afghan officials say the Taliban have been under increasingly heavy pressure from air strikes and army operations but the insurgents have repeatedly demonstrated their ability to inflict severe damage on Afghan security forces.
Several soldiers went missing after the attack during which one armored military vehicle was destroyed and two others were seized by the attackers together with weapons.
Afghan and U.S. commanders have been relatively upbeat about the course of the war since U.S. President Donald Trump announced a new and more robust military strategy previous year, with more air strikes and greater support for Afghan forces.
In January, the governor of Farah resigned, blaming political interference and corruption.
Saturday's attack came ahead of an expected increase in fighting with the end of winter and the approach of spring.