Does anyone know if there are any direct cruises from Nice to Malta?
By "cruises" do you mean ferries? If so, that would be one heckuva long ferry ride. If you are trying to get to Malta from Nice, I think you'll need to fly to Rome and then fly Air Malta to Malta. Or fly to Sicily. There are ferries from Sicily to Malta. Google it.
There is also a direct ship from Genoa Italy to Malta...don't know the price or the time required but I suspect it's at least 16 hours. You might find a better deal flying in.
take a plane.