Getting pop up message on MAC

Trying to stream games and I keep getting some bullshite virus alert that is clearly a scam. Keeps happening on every site I go to so it's obviously tied into me opening a video in Java(when I turn of Java no stream sites work so this isn't a solution). I cant figure out how to get rid of this crap it's incredibly frustrating just want to watch some football. Anyone have any ideas? I've done what they said to do on a few forums but it's failing completely. So lost right now.