She's way to young to understand "manners," or why making a mess would not be a perfectly delightful thing. She can and will learn from your reactions that you dislike certain behaviors, but is a long way from knowing why they might be right or wrong. And some babies love to watch their parents' reactions to throwing and dropping – to a baby, that can be downright amusing.
She's entered the "throwing stage" in which she has a completely normal craving to experiment constantly with throwing, gravity, and the results she gets from testing those. She's going to be there for a few months, and it is actually an important developmental stage during which she's learning a great deal of eye-hand development and gross motor skills, cause and effect, and so much more.
So I have two suggestions. (Three actually, starting with don't expect her to behave like a big person in a restaurant, because she simply can't yet.)
One is that you don't give her more that small amounts of anything on her tray or on the table in front of her. If she's experimenting with spoons, give her only enough to mush around a bit, and be prepared to remove it before she gets too bored or frustrated and "removes" it herself. If she's picking up and eating solids, give her only a couple of pieces/bites at a time. More may simply overwhelm her.
Second, Give her many legitimate opportunities to throw, swing her arms, bat with a soft object. Give her soft, throwable toys and a target – a box or basket on the floor nearby. Show her how to throw to the target. If she tries it with food or bowls, be prepared to calmly remove them and redirect her to the toys. She will begin to distinguish soon between what's okay to throw, and what's not.
And one final thing – keep your sense of humor and take lots of pictures/videos of the mess she makes. You will enjoy those someday. This phase is really not so bad if you keep the right attitude and don't expect more of your baby than she's able to give. Then come the Terrible Two's…