Mr Gibson later apologised and took down the post, saying he was not aware of the racial overtones of the term Shylock.
Labour leader David Cunliffe said he would have words with Mr Gibson, and did not know about the comments until yesterday. "I'm not happy with that."
Mr Gibson's move comes as some of National's campaign billboards have been defaced with anti-Semitic graffiti.
Mr Key said he was open about his Jewish heritage but his bigger concern was for the Jewish community.
"They're a good hard-working group of New Zealanders and I don't think people should be attacked on religious belief, whether they're Islamic, Christian or Jewish."
As for Mr Gibson's comments, "it's hardly 'Vote Positive', but again, we'll be letting that go through to the keeper as well".
Meanwhile, Dame Susan joined in condemnation of Mr Peters' "two Wongs don't make a right" crack on Sunday.
She said Mr Peters "needs to know he's not funny".
"His outdated rhetoric belongs in New Zealand's past -- it has no place in New Zealand's future."
Her comments were made after she came under fire from Dr Whyte, whom she had criticised two weeks ago for his "grotesque and inflammatory" comments that Maori enjoyed privilege comparable to pre-revolutionary French aristocrats.
Dr Whyte repeated his call for Dame Susan to resign, this time for failing to condemn Mr Peters -- which she later did. He ended his media release with a potentially defamatory joke at her expense.
"He's becoming very personal," she told the Herald last night. "This job's not for the faint-hearted and I'm not faint-hearted and if that's the way he wants to go then so be it."
She said both leaders' recent comments were likely poll-driven.
"We know that both of them probably enjoy the oxygen given to both of these issues."
Mr Key had a similar view about Mr Peters' joke. "It's Winston, isn't it? I don't want to be cynical about these things but we're 40 days from the election and you're asking me a question about it. He's probably achieved his objective, which is to try and get on the news."
Mr Cunliffe, who nine years ago was himself accused of mocking then National MP Pansy Wong's Chinese accent, said yesterday that he could see how people could find Mr Peters' joke offensive, but it would not stop Labour from potentially working with New Zealand First.
They said it
*"Shonky Johnkey Shylock" - Labour's Rangitata candidate Steven Gibson in a recent Facebook post.
*"Two Wongs don't make a right" - Winston Peters on Sunday.
*"Maori are legally privileged in New Zealand today, just as the aristocracy were legally privileged in pre-revolutionary France" - Jamie Whyte two weeks ago.
For full election coverage go here.