Well you could have just sent a letter. Violence, after all, is the last refuge of the incompetent.
Edit:
I have run the numbers and prepared a bill. In order to prevent the Medici from taking your action as hostile, we will permit you to purchase our goods and equipment for a price of 95,998 gold, payable in cash or goods. Since your attack continues to go through, we will be applying this debit to your accounts and will await your payment for remission of the debt. Seven (7) days will be provided for payment terms to be negotiated, after which collections agencies may be contacted.
Thank you. I hope you have a pleasant weekend.