The two leaders met in the Oval Office prior to an event at which they were expected to sign a deal for US participation in Ukraine's mineral industry.
But Zelenskiy openly challenged Trump over his softer approach toward Russian President Vladimir Putin.
Zelenskiy pushed back on Trump's claims that Ukrainian cities have been reduced to rubble by three years of war.
Trump stressed that Putin wants to make a deal.
"You are gambling with World War III," Trump told Zelenskiy at one point, urging him to be more thankful.
Vice President JD Vance interjected that it was disrespectful of him to come to the Oval Office to litigate his position, a point Trump agreed with.
"People are dying ... you're running low on soldiers," Trump told Zelenskiy as their meeting degenerated into a shouting match.
Trump told Zelenskiy he either needed to make a deal or the United States was out.
Zelenskiy urged Trump to make "no compromises with a killer," referring to Russia's leader.
Zelenskiy, who gained billions of dollars' worth of US weaponry and moral support from the previous administration under president Joe Biden for its fight against Russia, is facing a sharply different attitude from Trump.
Trump wants to quickly wind down the three-year war, improve ties with Russia and recoup money spent to support Ukraine.
Earlier, Trump welcomed Zelenskiy on his arrival at the White House before they headed for talks, lunch and then a joint press conference where they were to sign the agreement.
"I hope I'm going to be remembered as a peacemaker," Trump said.
Trump told Zelenskiy that his soldiers have been unbelievably brave and that the United States wants to see an end to the fighting and the money put to "different kinds of use like rebuilding".
The agreement negotiated in recent days would open Ukraine's vast mineral wealth to the United States but does not include explicit US security guarantees for Ukraine, a disappointment for officials in Kyiv.
Trump says the presence of US businesses would serve as a form of guarantee.
How much the deal would be worth to the United States is not spelled out.
Trump has said he expects to gain hundreds of billions of dollars.
Zelenskiy has said he would not sign an agreement that would put his country in debt for generations.
Ukraine would contribute 50 per cent of "all revenues earned from the future monetisation of all relevant Ukrainian government-owned natural resource assets" to a reconstruction fund jointly owned and managed by the United States and Ukraine.
The agreement does not specify how the funds would be spent, or identify specific assets it covers, although it says they would include deposits of minerals, oil and natural gas as well as infrastructure such as gas terminals and ports.
