"We did not talk about that in July," Zelenskiy said.
"There was no blackmail."
Trump asked Zelenskiy to "investigate" Biden and his son during the call, as revealed in a rough copy of the White House. Congressional Democrats believe that Trump has withheld military assistance to put pressure on Ukraine and advance its domestic interests ahead of next year's US presidential election.
The July call is central to the impeachment investigation and has embarrassed Zelenskiy for liking Trump and being critical of European partners whose support he needs to strengthen the Ukrainian economy and end the conflict with Russia.
He said that he had "not even checked" whether the Ukrainian transcript of the July call coincides with that of the White House, but said: "I think they agree."
Trump later said military aid was frozen due to concerns over corruption in Ukraine, but the move sparked an outcry from Congress and the money was released in September.
Zelenskiy said, however, that the call "was not associated with arms or history with (the Ukrainian gas company) Burisma", in which Biden's son Hunter served at the blackboard.
Asked what Ukraine has done to move the US to release aid, Zelenskiy said: "We have many diplomatic contacts. And if we need to find a solution to questions at this level, questions about the security of our country, we will use all our powerful capabilities. "He did not respond.
"I do not want to interfere with the elections in any way," he said in the US. Zelenskiy appears to be playing in both US political camps to ensure that Ukraine continues to receive support, regardless of who wins the presidential election next year.
Zelenskiy said he thought the call would lead to a personal meeting with Trump and wanted the American leader to come to Ukraine. Zelenskiy said the "key question" for him was to persuade the White House to change "his rhetoric" about Ukraine as a corrupt and untrustworthy country.
He said he wanted to meet with Trump in person, but there were "no conditions" for such a meeting.
He said he made "several phone calls" with Trump, but he wondered about repeated questions about their relationship. "We are an independent country, we have relations with many countries," he said.
Television and film comic Zelenskiy overwhelmingly won the presidency in April for promising to fight corruption and end the five-year conflict with Moscow-backed separatists in eastern Ukraine. He cautiously seeks further support from the US as he seeks to make peace with the powerful neighbor, Russia.
Most questions of the unusual media event on Thursday related to the Russia conflict or the economic problems of Ukraine.
In the July call, Trump sought help on two fronts. The first concerns Trump's claims that Ukraine has teamed with the Democrats to derail its 201
At the same time Trump also urges Ukraine to investigate possible misconduct of the bidens. Trump said the United States has an "absolute right" to call on foreign leaders to investigate corruption cases, although neither the former US Vice President nor his son has provided evidence of criminal misconduct.
Zelenskiy also joked about Trump's Twitter missives and said he did not expect any change in US-Ukrainian relations in the future, "but if so, we'll find out about it on Twitter."