Start by getting a monopod to hold the camera steady. It could just be your hands moving. If it is motion blur from the players, then you need a faster shutter speed. There are two ways to get a faster shutter speed, wider aperture, or higher ISO setting on the camera.
Getting a wider aperture is usually expensive. That means a new lens.
Higher ISO setting means more noise in the picture. Your camera goes to ISO 12800. Start by bumping to ISO 1600 and see what you get.