Huawei Technologies Chief Financial Officer Meng Wanzhou was arrested in Canada on Dec. 1 on a U.S. extradition warrant. Huawei is suspected of evading American sanctions on Iran, a possibility that U.S. prosecutors have been investigating since 2016.

The arrest was made on the same day that Trump and Xi met for dinner amid high-level trade and national security talks in Buenos Aires. An unnamed senior U.S. official with direct knowledge of the matter told The Washington Post last week that Trump learned of the arrest only after the meal had concluded and reacted with intense anger.

Kudlow agreed that Trump did not know about the arrest at the time but said he was not angry on learning about it after the dinner.

"He did not know," Kudlow said on "Fox News Sunday." "He did not know, and he had no reaction afterward. . . . He didn't know. I'll just state that unequivocally. He learned way later."