Competition you have a reff e.g. in Judo you would say "mattae" (meaning stop in Japanese).
Real fight you either split it up, or stop it when some guy is getting kick in the head on the floor non-stop.
If you are the judge you call time out, break, yame, matte, depending on the tournament. If you are the competitor you can not, at least not in any tournaments I go to.
The referee can call time out.
