The EU is hosting Zelenskiy in Brussels as missiles and drones rain down on Ukrainian cities, amid fears the US could pull back intelligence sharing and weapons support from Kyiv.
President Trump blindsided Zelenskiy last weekend with a surprise announcement that Ukraine and Russia had agreed not to target each other's energy facilities.
But in the days that followed, Russia rained down missile and drone strikes, including on energy targets such as power stations, knocking out power to hundreds of thousands of Ukrainian people.
Trump last week abruptly lifted sanctions on Russian diesel and has blamed Ukrainian strikes on Russian refineries for pushing up energy prices that could cost him at the ballot box in US midterm elections in November.
He also last week called for Zelenskiy to be replaced.
In an interview published on Thursday, the Ukrainian leader told the Financial Times that his country's patience had run out.
"The block (on attacking refineries) is out. We're done," he said, before Ukraine struck a Russian oil refinery.
As he arrived at the summit, Zelenskiy said he would discuss Ukraine's needs for the rest of 2026 and for 2027.
Ukraine wanted to end its war with Russia as quickly as possible but did not see "signals from the Russian side that they are ready for this", he said.
"That's why we have to prepare for the winter," he said.
"The winter package is not only energy, it's also air defence and funding."
In an interview with the Newsmax news outlet, Trump said: "All he's doing is making the world oil price higher. Well, I think that's a disgrace."
EU leaders have hit out at Trump's diesel deal with Russia, though they are also grappling with soaring energy prices since the Iran war that have exposed divisions between member states.
EU Commission President Ursula von der Leyen told reporters before the summit on Friday that the bloc would continue to support Ukraine and not lift any sanctions against Russia "unless Russia stops this war".
Dutch Prime Minister Rob Jetten said he was unhappy with the number of countries that had been willing to pledge new financial support to Ukraine.
"But we will see several countries pledging more military support soon," he said.
"Today will be more about talking to Zelenskiy about how to deal with the complex diplomatic situation that has arisen and how to survive the winter."
Earlier in October, Zelenskiy told Reuters Ukraine had agreed a plan with European partners that would allow it to close a $US27 billion ($A39 billion) deficit in its military spending for this year, allowing it to order the drones needed to continue fighting at the start of 2027.
However, Ukraine Finance Minister Sergii Marchenko recently said the nation still faced an unfunded budget gap for 2027 of $US32.6 billion - and that does not include an estimated $US40 billion in direct military supplies from allies.
Belgian Prime Minister Bart De Wever said Zelenskiy "will probably look everybody straight in the eye and say, thank you for the 90 billion (euros), but that money is going to run out because a war is a very costly thing."
President Vladimir Putin played down the effect of Ukrainian attacks on Russian refineries, saying they had caused "nothing particularly significant".
Russia has moved to place local assets of French, German, Swedish and Dutch companies under temporary management, in retaliation for the EU's support for Ukraine.
In the latest attacks, Russian drone strikes on the city of Kharkiv killed three people, according to local authorities, while strikes on the Volyn region bordering Poland left 370,000 people without power.
Emergency power cuts were introduced in the Ukrainian capital Kyiv during Russian strikes, private energy provider DTEK said on X.
