About blocked attacks?

Every day or two I get an alert from my Norton Internet Security that its blocked an attack
from this location: Attacking computer= 72.51.44.40, 80
and attacking URL= 72.51.44.40/1845/ and it says its a "malicious toolkit website 9"
and that the attack came through my Firefox browser.

Is there a way to send a nasty message back to the attacking URL
or computer to let them know I am aware of thier activity?

Can I block that computer or URL completely from my system?
Can I report them to some organization?

 

Thanks for any help.