U.S. President Donald Trump on Monday said that he did not tell Ukrainian President Volodymyr Zelensky that Ukraine will receive assistance from the United States only if the country launches an investigation into activities of U.S. presidential candidate Joe Biden.

"No, I didn't," Trump told reporters in a meeting with Poland's President Andrzej Duda when a journalist asked Trump if he told the Ukrainian leader that they would have the aid only if they investigated Joe Biden and his family.

Trump said that he "had a very nice call" with Zelensky.

"It was really a congratulatory call because he had just won," Trump said.

Some U.S. media earlier reported that Trump on July 25 tried in a phone conversation with Zelensky to ask the Ukrainian president for an investigation of Biden in exchange for the military aid. They also reported that Trump around eight times for the Bidens to be investigated and work with attorney Rudy Giuliani on the matter.

Some media reported that Trump trying to launch the investigation against Biden's son, delayed the provision of military aid to Ukraine.