Yes, although "fighting words" arguments are losing clout in most courtrooms, it appears as if these Muslims were calling for direct violence, which isn't protected under the 1st Amendment.
What precisely were they saying and in what context? It could possibly fall under the "imminent lawless action" clause in the 1969 Brandenburg v Ohio judgement, although it appears most likely that the First would cover it. It all depends.
Were they calling for direct violence kind of, well, in a few minutes? Or is it just a vague call? It's all details.
Are there similar cases in the States we could refer to?
Reuters has a say on U.S. free speech cases - they give a mention to a racist preacher inciting violence there and, of course, the often-amusing Fred Phelps.