After the election, he said that Mexico would "reimburse" the US.
Later in the day, Trump contemplated introducing a 20% import tax for products from Mexico to pay for The Wall.
The White House today proposed a 20-percent tax on imports from Mexico as a way to fund the wall President Donald Trump wants to build on the U.S.' southern border.
"I think that, to put it in cinematographic terms, Trump is not 'Terminator, ' he's a negotiator", Slim said, referring to the science-fiction film about a killer cyborg from the future. "I work with the Mexican people all the time - great relationships", Trump said. "On top of that, the border is soft and weak, drugs are pouring in", he said, without providing specifics. He said that 50 Mexican consulates in the United States would be used in defending the rights of immigrants in the country.
Mr Trump also insisted the USA would recoup the costs for the barrier from Mexico, which has strongly objected.
According to a the press secretary, the two spoke for an hour and it was a "productive and constructive call regarding the bilateral relationship between the two countries".
"I will say that we had a very good call", Trump said in a news conference at the White House. Mexico's government also said the flow of illegal arms and drugs across the border was discussed, and said the United States trade deficit also came up.
But in a televised message to his country, Mr Nieto reasserted that Mexico would not pay a single peso towards it.
He said that Trump had a desire to "return to the past" where the United States was an industrial power, describing such a move as a bad idea.
He also issued draft executive orders that, if signed, would freeze the United States refugee programme and bar Syrians from it altogether.