It also announces the emergence of North Korea as a “fully fledged nuclear power", reported Independent.
It is believed the letter, written by the Foreign Affairs Committee, was sent to a number of Western countries covertly.
But its existence has been made public by Australian Foreign Minister Julie Bishop, who received it after it was passed to Australia's Indonesian embassy by the North Korean consulate in Jakarta, according to the Sydney Morning Herald.
The author of the message and the way it was delivered is said to be unusual — North Korean communiques to the West are usually published through state news agency KCNA.
Addressed to the “parliaments of different countries”, it condemned Mr Trump’s rhetoric at the UN, in which he promised the US could “totally destroy” North Korea, also known as DPRK.
“If Trump thinks that he would bring the DPRK, a nuclear power, to its knees through nuclear war threat, it will be a big miscalculation and an expression of ignorance,” said the letter.
It continued: “The DPRK has emerged a fully-fledged nuclear power which has a strong nuclear arsenal and various kinds of nuclear delivery means made by dint of self-reliance and self-development. The real foe of nuclear force is a nuclear war itself.
“The Foreign Affairs Committee … takes this opportunity to express belief that the parliaments of different countries loving independence, peace and justice will fully discharge their due mission and duty in realising the desire of mankind for international justice and peace with sharp vigilance against the heinous and reckless moves of the Trump administration trying to drive the world into a horrible nuclear disaster.”
Ms Bishop told the Herald: "This is the first letter that we can find that any Australian foreign minister has received from North Korea... it's an open letter, this is not how they usually send messages around the world."
"I read this as showing that the collective strategy of allies and partners to impose maximum pressure and diplomatic and economic sanctions on North Korea is working,” she added.
The minister said the letter was a “desperate” attempt to divide the international community and showed North Korea was feeling isolated.
The US is the backbone of an alliance of countries that are highly wary of North Korea, including South Korea, Japan, the UK and Australia.