Generally, when someone says something like "left wing groups" they mean something with a formal organization.

"Antifa" is less of an organization than even some loose collective like "anonymous"

Are there left-wing agitators? Sure, black bloc and other "direct action" protestors have been around since at least the world trade protests in the 90s.

But to the best of my knowledge there isn't really a formal "antifa" organization to dismantle or anything.