Trump also said his patience with Iran is running out and Tehran had to make a deal.
With official agreements from the US-China summit yet to be released, Trump's comments gave little indication of whether Beijing, the main buyer of Iranian oil, might use its influence with Tehran to end a conflict it said should never have started.
"We've settled a lot of different problems that other people wouldn't have been able to settle," Trump said on Friday after he met Xi in Beijing on the second day of talks which included the Iran war, Taiwan, trade and other issues.
Xi did not comment on his discussions with Trump about Iran, although China's foreign ministry issued a blunt statement outlining Beijing's frustration with the Iran war.
"This conflict, which should never have happened, has no reason to continue," the ministry said.
Iran effectively shut the strait to most shipping traffic in response to US-Israeli attacks which began on February 28, causing an unprecedented disruption to global energy supplies.
The US paused its attacks on Iran in April but began a blockade of the country's ports.
Tehran said it would not unblock the strait until the US ended its blockade.
Trump has threatened to attack Iran again if it does not agree a deal.
"We don't want them to have a nuclear weapon, we want the straits open," Trump said in Beijing on Friday.
Iranian Foreign Minister Abbas Araqchi said Tehran had received messages from the US indicating Washington was willing to continue talks and engagement.
Iran, which denies it intends to build a nuclear weapon, has refused to end its nuclear program or relinquish its hidden stockpile of enriched uranium, to Trump's frustration.
"I am not going to be much more patient. They should make a deal," Trump said in an interview aired on Thursday night on Fox News.
After talks between Trump and Xi on Thursday, the White House said Xi had made clear China's opposition to any Iranian effort to charge a toll for use of the strait.
Trump said Xi also promised not to send Iran military equipment.
The war has become an electoral liability for Trump as it drags on towards key US midterm elections in November.
Analysts doubt Xi will be willing to push Iran hard or end support for its military, given its value as a strategic counterweight to the United States.
"I don't need favours," Trump told reporters on his plane returning from Beijing, when asked if he had requested help.
Talks on ending the war, mediated by Pakistan, have been on hold since Iran and the US each rejected the other's most recent proposals.
Foreign Minister Araqchi said on Friday Iran would welcome any Chinese input, adding that Tehran was trying to give diplomacy a chance but did not trust the US.
Araqchi reiterated that vessels not linked to states attacking his country could traverse the Strait of Hormuz.
The UAE said it would speed up building a new pipeline to its Fujairah port just outside the strait, after a vessel heading to it was sunk and another was boarded and redirected to Iran.
Thousands of Iranians were killed during the US and Israeli air strikes, and thousands have been killed in renewed fighting in Lebanon between Israel and the Iran-backed group Hezbollah.
With a fragile ceasefire in Lebanon due to expire on Sunday, discussions between Lebanese and Israeli officials were set to continue on Friday after what a senior State Department official said were productive talks on Thursday.
