I know geese can be aggressive. It's up to your neighbor to keep them off of your property. I would go over and tell your neighbor that his or her geese are on your property and it's a problem. If your neighbor doesn't do anything about it, I would call your local animal control officer. Usually a visit by the animal control officer convinces people to get their animals under control.
I had a situation where my neighbor let their dogs roam, and the dogs were coming over to my farm and killing my chickens. I went over to the neighbor's house and nicely told him that his dogs were killing my chcikens, and he said, "Well that's what dogs do." I asked him to keep his dogs off of my property and he refused. I called the animal control officer, who came right over, and showed him the dead chickens. He went over to my neighbor and told him that he had to pay me $50 for each chicken that was killed, and if it happened again, he would have to pay for the chickens and pay a $1000 fine. Suddenly, I never saw his dogs on my property again. The animal control officer is your friend.