Demonising your enemies as racists or fascists, ie nazis and employing mob tactics to "no platform" them or otherwise shut them up as in "no free speech for racists", strike me as exactly the sort of tactics the real fascists employed in the 1930s. So in that sense, yes, Antifa groups/coalitions/collectives/networks frequently behave like fascists. Which is no surprise really if you subscribe to the horseshoe model of the political spectrum.