REUTERS/Darren Staples
A worker stacks bars of chocolate at Cadbury World in Birmingham, central England, October 7, 2008.
The petition on MoveOn.org has nearly 15,000 signatures.
"Of one of your weaknesses comes in the shape of a Toffee Crisp, Maltesers, Yorkie, Cadbury, or Rolo your taste buds may soon be challenged," the petition reads.
Hershey recently struck up a deal with Let's Buy British Imports to stop imports of Cadbury products made overseas, reports Tatiana Schlossberg at The New York Times.
The company will also stop importing British Kit Kat bars, Toffee Crisps, and Yorkie chocolate bars.
Fans of chocolate manufactured in Britain say it tastes better than American-made chocolate.
A Hershey's representative told The New York Times that the company has the rights to manufacture Cadbury chocolate in America using different recipes, and that importing British chocolate is an infringement.
American fans of British chocolate are furious about the agreement.
In addition to the online petition, protestors have started the hashtag #BoycottHershey.
#boycotthershey .... so close to not having to eat chocolate that tastes of baby sick .... Get boycotting ???? get importing ???? @hersheys
- PrintS JacKsoN (@printsjackson) January 27, 2015
Hey #hersheys - maybe if you made better chocolate you wouldn't have to resort to blocking the competition. #boycotthershey
- faisal sultan (@friskygeek) January 27, 2015
FREE TRADE @Hershey #stophershey #boycotthershey Any way, any how, I will always be able to get my @Caburys ....You @Hershey are disgraceful
- Michele Rosborough (@micheleros) January 26, 2015
#BoycottHershey Why should you @Hersheys dictate what chocolate we eat? Looks like yet another american company I will avoid supporting now.
- David Withheld (@Cuisee) January 27, 2015