Larry Kudlow, the economist and former adviser to President Ronald Reagan, said he’s not in favor of any plan by the Trump administration to slap tariffs on imports as a way of protecting U.S. industry.

“I am a free market guy,” Kudlow said on CNBC.  “Unless you can really prove a case that a foreign country is not playing by the rules or is clearly subsidizing. I am a free trader. Trump and I disagreed on it during the campaign.”

Kudlow was an economic adviser to Republican Donald Trump’s presidential campaign who recommended tax cuts, less regulation and letting U.S. companies bring overseas cash back to the country without punishing double taxation. During the campaign, Trump pledged to help American workers by seeking new trade deals that would dissuade U.S. companies from closing factories and moving them offshore.

President Trump this week engaged his Cabinet in a debate over his desire to impose tariffs on large exporters like China, clashing with the majority of his advisers, according to Axios.

According to "administration sources," Trump met with 24 of his Cabinet members, advisers, and members of his administration, including Vice President Mike Pence. Trump, Pence, and a small group of advisers expressed their intent to impose tariffs of around 20 percent on steel and other imports, including semiconductors, aluminum, paper and appliances.

Reuters reported on Wednesday that "Trump is growing increasingly frustrated with China," and is weighing trade actions against the country over its policy towards North Korea and its trade deals.

The move is driven by Trump's base of support, although many of his advisers warned that tariffs would affect more than just China and a number of allied nations, including the United Kingdom, Germany, Canada, Japan and Mexico.

Kudlow said he’s only in favor of temporary tariffs as part of broader negotiations between two countries to open and expand trade.

“If you can prove that by law you, can impose temporary targeted tariffs. Many presidents have done that,” Kudlow said. “I'm in favor of temporary tariffs and then you work it out between the two countries.”

Kudlow said Trump’s threats and pronouncements on trade are part of a negotiating strategy with other countries. Kudlow said he doesn’t want to see a trade war that ends up hurting the global economy.

“The bark is bigger than the bite, right?” Kudlow said. “President Trump establishes a U.S. preference himself, but will work with other people.”

 Trump is scheduled to meet with world leaders at the G20 summit next week.