White House economic advisor Larry Kudlow told CNBC on Monday that President Donald Trump is warning China about its trade practices with tariffs.

"This president's got some backbone, others didn't and he's raising the issue in full public view, setting up a process that may include tariffs. Hopefully, it will be mostly negotiations," Kudlow said on "Squawk on the Street." "I don't know if we'll have tariffs or not."

"[Trump] is responding to decades of misdeeds by China [on] trade," said Kudlow, an ex-CNBC contributor and a former Wall Street economist. "It's high time we did that."

"Somebody's got to do it. Somebody's got to say to China, 'you are no longer a Third World country. You are a First World country and you have to act like it,'" he said. "The president's got to stick up for himself and the United States."

In a tweet early Monday, Trump called out China again for what he has said are unfair trade practices by the world's second-largest economy.

@realDonaldTrump: When a car is sent to the United States from China, there is a Tariff to be paid of 2 1/2%. When a car is sent to China from the United States, there is a Tariff to be paid of 25%. Does that sound like free or fair trade. No, it sounds like STUPID TRADE - going on for years!

The president unveiled a list of Chinese imports last week that his administration aims to target as part of its crackdown on China. Shortly after the announcement, the Asian nation announced additional tariffs. China's Foreign Ministry blamed the United States on Monday for trade friction and said that it was impossible for negotiations to take place under current conditions.

Stocks were higher Monday as the Trump administration tried to soften its tone regarding trade relations. During a "Fox News Sunday" interview, Kudlow tried to calm trade war fears but added Trump was "not bluffing" on tariffs. Treasury Secretary Steven Mnuchin said Sunday he does not expect a trade war between the U.S. and China to take place.

Trump last month picked Kudlow to succeed Gary Cohn as director of his National Economic Council. Cohn, former No. 2 executive at Goldman Sachs, resigned from the White House role shortly after losing his fight to persuade the president not to impose import tariffs on steel and aluminum, an earlier move separate from the latest China tariffs over what the U.S. considers Chinese companies' theft of American intellectual property.

Saying he supports almost all of Trump's policies, Kudlow on Monday reminded viewers he did not like the across-the-board steel and aluminum tariffs announced last month. But he said Trump fixed that with the exemptions that included Canada and Mexico, pending a successful reworking of the 1994 North American Free Trade Agreement.

"I have no specifics to offer this morning, but I will say progress is being made on renegotiating and recalibrating NAFTA. Good progress is being made on that," Kudlow added.