On China's trade surplus, Mr Trump surprised many when he said he did "not blame China" for "taking advantage".
China has said it will lower market entry barriers to some sectors.
The US president was speaking in Beijing while on a state visit.
He is in the Chinese capital as part of his five-nation tour of Asia. The two leaders held talks earlier on Thursday after a grand welcome for Mr Trump.
China will further lower entry barriers in the banking, insurance, and finance sectors, and gradually reduce vehicle tariffs, the Chinese foreign ministry said.
Deals worth $250bn (£190bn) have also been announced, although it is unclear how much of that figure is past deals being re-announced or simply potential future deals.
But Secretary of State Rex Tillerson told journalists the deals were "pretty small" in terms of tackling the trade imbalance.
Trump tried to cajole Xi on Pyongyang
Discussion on how to deal with North Korea's threats to the region has dominated Mr Trump's agenda, and China is Pyongyang's main economic supporter.
Mr Trump said China could fix the problem of North Korea's nuclear programme "easily and quickly".
He added: "I am calling on [Mr Xi] to work very hard. I know one thing about your president. If he works on it hard, it'll get done."
Mr Xi, for his part, said both sides would "continue to work towards" fully implementing UN sanctions and "enduring peace" on the Korean peninsula.
Mr Trump has previously been more critical and tweeted in July that Beijing was doing "NOTHING for us with North Korea, just talk".
Just before his arrival in Beijing he urged China to sever ties with the North. Beijing has consistently said it is doing all it can.
He swerved away from blaming China for the trade deficit
"I don't blame China - after all, who can blame a country for taking advantage of another country for the benefit of its citizens... I give China great credit," said Mr Trump while addressing a room of business leaders.
Instead, the US leader said previous US administrations were responsible for what he called "a very unfair and one-sided" trade relationship with China.
Mr Trump has in the past accused China of stealing American jobs and threatened to label it a currency manipulator, though he has since rowed back on such rhetoric.
Mr Xi on Thursday promised "healthy" and "balanced" economic and trade relations.
The two leaders also said they would to work together to tackle terrorism and drug trafficking. Mr Trump upheld the "one China" policy in his talks with Mr Xi, Xinhua state news agency reported.
He has poured praise on Xi
Since arriving in Beijing, Mr Trump has been fulsome in his praise for the Chinese leader, saying at one point: "You are a very special man."
He has also enthusiastically thanked Mr Xi for his hospitality in several tweets.
Mr Trump flew into Beijing on Wednesday and was greeted with great pomp and ceremony, in what was billed as a "state visit-plus".
He has tweeted several times since arriving in China - where Twitter is banned. But a White House official told reporters that he would "tweet whatever he wants".
As part of his Asia trip Mr Trump has already visited South Korea and Japan, and will go on to Vietnam and the Philippines later in the week.
What's Trump done so far in Asia?
- He's warned North Korea to "not try" the US and the world.
- But he also called on Pyongyang to "come to the table" for a disarmament deal.
- He said Japan and South Korea will be buying US military equipment which could shoot down Pyongyang's missiles - the two countries said they are considering it.
- He's also lashed out at "unfair" trade ties with Japan - while in Tokyo