The newspaper columnist appeared on Fox News to hit back at the Harry Potter author after she criticised Hopkins' description of Britain being "cowed" by last Wednesday's events.
Rowling, 51, tweeted that the 42-year-old's comments reminded her of pro-appeasement US ambassador Joseph Kennedy - father of President John F. Kennedy - who believed Britain would lose the Second World War.
On Tuesday, Hopkins appeared on Fox where she slammed the best-selling author.
She also tweeted a clip of her comments with the words "my message for Liberal luvvie" JK Rowling.
Speaking on the show, Hopkins said: "JK Rowling writes for children and she writes about a fantasy land.
"If she wants to believe a fantasy land where we're all getting on well together and it's a brilliant, marvellous place and it's absolutely fine, no problem that someone mows down people as they cross a bridge, we'll leave that up to JK Rowling."
The former Apprentice candidate added: "Darling, carry on writing your fantasy land books.
"If you think England is united that's a fantasy as well."
Hopkins also said of Rowling: "Seeing as you're such a big fan of migrants why not spend some of your billions in homing those migrants while you're at it."
The Sun and Daily Mail contributor provoked a response from Rowling when she said of the terror attack: "People are cowed, people are afraid and people are not united. Great Britain is more disunited, more divided than at any other time in its past."