He said challenges from Australia and UK were pushing up costs and the loan was quickly running out.
"The trust has just wrapped up a series of hui around the country, which has confirmed Māori wanted the name mānuka protected.
"Going forward the way we fund legal proceedings is the challenge but with the industry, iwi and the government we are working through our funding constraints,"he said.
He said the mānuka honey industry equated to $436m in exports last year alone so the industry was worth fighting for.
"It's great that iwi, the industry and the government want to come to the party to support this but we need a more sustainable model because the fight and litigation to protect the term manuka will take some time."
Goldsmith would not disclose how much of the $1.7m grant was still available and said it was hard to say how much more was needed.
"How long is a piece of string, we just don't know. We have a ball park figure and we don't want to disclose that yet because we are working on the detail."
He said a recent review by Price Waterhouse Cooper found the trust's strategy was on the right path.
"We are confident we will win this fight, it's a legacy issue for us to protect mānuka for the next generations as a taonga."
"We asked Minister for Economic and Regional Development Stuart Nash if the government is considering allocating more money to the cause through The Provincial Growth Fund but did not get a response."
- RNZ