Two months before Trump is expected to visit Beijing, Xi agreed to hike soybean purchases from the US to 20 million tons in the current season, up from 12 million tons previously, Trump said.
Soybean futures rallied sharply after the announcement.
The ailing US farm belt is a major domestic political constituency for Trump and China is a major consumer.
Along with the goodwill gesture, Xi also warned Trump about Taiwan.
"The United States must carefully handle arms sales to Taiwan," Chinese authorities said in an official summary of the meeting.
Trump and Xi's call was held hours after Xi's virtual meeting with Russian President Vladimir Putin.
"All very positive," Trump said in a post on his Truth Social platform.
"The relationship with China, and my personal relationship with President Xi, is an extremely good one, and we both realise how important it is to keep it that way."
Trump and Xi last spoke by phone in late November, after which Trump touted "extremely strong" relations with China.
Following months of trade tensions triggered by Trump's tariffs last year, relations between the United States and China stabilised after a meeting between the leaders in October in South Korea, where a fragile trade truce was struck.
