WASHINGTON (AFP) - Mexico is willing to talk with the United States in order to maintain good relations, but paying for President Donald Trump's border wall "is not negotiable," Mexican Foreign Minister Luis Videgaray said on Thursday (Jan 26).

"There are things that are not negotiable, things that cannot and will not be negotiated. The fact that it is being said that Mexico should pay for the wall is something that is simply not negotiable," Videgaray said during a press conference at the Mexican embassy in Washington.

Holding true to his campaign promise, Trump on Wednesday ordered US officials to begin to design and construct a wall along the 3,200-kilometre US-Mexico border.

The White House has since then floated the idea of a 20 per cent tax on Mexican imports to cover the cost of the wall, but later backtracked and called it just one idea among many.

Such a tax, Videgaray said Thursday, would only harm Americans.

"Here in the United States avocados, washing machines, televisions, many things that North American families like to buy and that are expensive, would cost more," he said.

"It would be the American consumer who would be paying," Videgaray added.

The top diplomat was at the White House Thursday to help pave the way for a visit by Mexican President Enrique Pena Nieto when his team received word of a Trump tweet suggesting that if Mexico were not willing to build the wall it should cancel the trip.

Pena Nieto tweeted later that he had informed the White House that he would "not attend the working meeting" next week.

"We recognise that it is the beginning of a new relationship with President Trump and his government. We recognise that, as President Pena Nieto has said, we are ready to negotiate. We have clear priorities and objectives," Videgaray said.