Elsewhere on Thursday, leaders gathering for the European Political Community in Budapest discussed Trump's return to the White House.
Ukrainian President Volodymyr Zelensky said he had a "very warm" and "productive conversation" with the president-elect.
"But we have to do everything to ensure that the results of our interaction between Ukraine and America, the whole of Europe and America, are productive and positive," he added.
Many in Ukraine and Europe are worried that Trump might slow, if not halt, the flow of American military aid to Kyiv upon taking power in January.
UK Prime Minister Sir Keir Starmer assured Zelensky at the summit that the UK's support for Ukraine in its war with Russia remains "iron-clad".
Hungarian Prime Minister Viktor Orban - who previously said he celebrated Trump's win by "tapping into the vodka supply happily" - said the US and Europe now face tough talks on trade.
Orban, who is a close ally of Trump, told a press conference that "the trade issue with the US will come up and it will not be easy".
Before winning the election, Trump said he would impose tariffs of 10% on all imports.
“There was an agreement that Europe should assume greater responsibility for its own peace and security in the future. To put it even more bluntly, we cannot expect Americans to be the only ones to take care of us," Orban said.