Ive been asked to make a statemnet to the police, do i have to?

a man passed my gate with a shitzu, my german shepard and my labrador were in my garden, the shitzu owner then claimed that my labrador approached him and he fed him a biscuit, he than claimed that my german shepard came out to him and attacked his shitzu. my partner was in the house at the time and came out of the house to see what said man was shouting at. he admitted to feeding my dog and said that he was going to call the police. My partner cannot be sure as to weather the gate was open, but he came in the house and my shepard was in the garden and when he came back out the shepard was still in the garden. The police arrived and asked me to sign a form stating that my dog was to be kept undercontrol at all times and that a copy of this was being sent to the dog warden and the form would also be used in evedance should he "attack" again. i refused as there were no witnessess to this and ive now been asked to attend the police station to make a statemnet. do i have to do this?