Zelenskiy told a European Union summit in Brussels that Russia did not want peace.
EU leaders rallied around Zelenskiy after Trump again criticised Ukraine, calling its strikes on Russian refineries a "disgrace".
The EU was hosting Zelenskiy at one of the most difficult moments for Ukraine, with Russian missiles and drones raining down on Ukrainian cities and fears the US could pull back intelligence-sharing and weapons support from Kyiv.
Zelenskiy showed little sign of softening his stance toward Washington.
Trump blindsided Zelenskiy last weekend by announcing that Ukraine and Russia had agreed not to target each other's energy facilities.
Ukraine struck a Russian oil refinery southeast of Moscow on Thursday, after Zelenskiy declared that Kyiv was abandoning the energy ceasefire that Trump had announced.
The US diesel deal with Russia angered Ukraine and its European allies.
"And now we can see how cash will start flowing back into Russia through the diesel deal," Zelenskiy told reporters.
"This diesel deal will never be enough to offset the impact of the Strait of Hormuz on global markets. But it will put more money straight into Putin's pocket to fund this war."
French President Emmanuel Macron said the deal "is not good for anyone. It sends a negative signal. It is an element of division and doubt."
Zelenskiy accused Putin of not being interested in any sort of peace talks.
"Putin does not want peace talks at the moment, in any form," he said. "He's playing with words, claiming they respond... Quite simply, it looks like a parody of a genuine desire to end the war."
Putin struck a hawkish and confident tone in addressing senior commanders on the need for security zones in response to Ukraine's 2024-25 incursion into Russia's western Kursk region.
"Our goal is to ensure the absolute security of Russia's border regions for the future, and we do not plan to make this a subject for potential peace negotiations with Ukraine," he said in comments broadcast on Russian television.
The Kremlin said last week Ukraine had undermined the possibility of an immediate resumption of peace talks after it had hit Moscow with drones during last month's Russian parliamentary election.
Putin's investment envoy, Kirill Dmitriev, said Russia and the US were discussing a range of joint projects, including nuclear-powered data centres following the agreement on diesel.
In his comments in Brussels, Zelenskiy said the operation of Starshield, the military-grade version of Starlink, had improved but was not yet fully restored, adding the disruption placed civilians at risk.
Trump, speaking to reporters in Washington before heading off to attend a rally in Georgia, denied he or Elon Musk were behind the reduction in the system's capability.
"It wasn't me, and I don't think it was Elon, and from what I understand it's the same as it's always been," he said.
Asked about his relationship with Zelenskiy, he said: "I think it's good. I want him to do one thing: settle the war."
