President Trump always accused the anti-fa and far left for causing violence on his "innocent" supporters. He even taunted the anti-fa during his presidential debate. 

Anti-fa is basically anti-fascist movement who targetted alt-right and fascist forces whether it is within or outside the government. 

They use different tactics to disrupt the events held by alt-right groups which they deem fascists by carrying pepper spray, knives, bricks and chains.

Antifa defends the use of violence to combat the “fascist” forces.

Anti-fa has always called out the Trump administration's levels of surveillance, incarceration, deportations, and police brutality and murders against the US Public.