US courts, across various states, have been trying to define 'moral turpitude' for years!
However my second link, above, goes to the definition which the U.S. Department of State Foreign Affairs actually uses for immigration purposes.
(AAAGH!!! I've just checked. For some strange reason, my link is dead. With a bit of luck, this should work instead:
http://tinyurl.com/3afsm8g )
Since the USA doesn't have laws specifically against 'harassment' it's not listed in either the 'included' or 'excluded' categories used when determining what is, or isn't, moral turpitude. I'm guessing that it's not moral turpitude but it would be up to the US Embassy to make their own decision.
It's up to you to decide for yourself whether you want to 'chance it' and seek an ESTA. However if you decide to apply for a visa there's nothing a travel agent can do to help you. You need to apply directly to the US Embassy, submitting your Police Certificate and other relevant documentation:
http://london.usembassy.gov/b2.html
Chris