Nationalist Duda, whose term in office expires in 2025, was one of Trump's preferred international partners during his presidency.
"I was invited by Donald Trump to his private apartment, so to speak... this is simply a private meeting in connection with my presence here in New York," Duda told reporters in New York.
"We will talk about our cooperation... We just know each other as people, as two, I can say in a sense, friends."
Trump, who is on trial in New York over a hush money payment to a porn star, is in a tight race against President Joe Biden, a Democrat, ahead of the November presidential election.
Many European leaders have long been nervous that another Trump presidency would mean waning U.S. support for Poland's neighbour Ukraine and the NATO military alliance.
(Reporting by Alan Charlish and Karol Badohal; Editing by Lisa Shumaker)
