The American president's comment came when he was asked whether he believed his Ukrainian colleague was willing to give up the Russian-occupied area, which Trump responded to with "I think so".
Zelenskyj has, however, rejected a legal recognition of Crimea as Russian.
The Ukrainian Crimea was annexed by Russia in violation of international law in 2014, after Russian forces had taken control of the territory the same year. Russia's full-scale war of aggression in Ukraine began just over three years ago.
