Foreign Minister Radosław Sikorski said he was "disappointed that President Zelensky did not take into account Poland's historical sensitivities."
He warned, however, that any Polish-Ukrainian quarrel over the past would have one clear winner: Vladimir Putin.
Earlier in the day, Polish President Karol Nawrocki said he would propose that Zelensky be stripped of a prestigious Polish state honour.
"Decorations are a presidential prerogative," Sikorski told reporters when asked if Nawrocki would act on his threat against Zelensky.
He noted that there was historical precedent: in 1990, President Wojciech Jaruzelski revoked the Virtuti Militari cross awarded to Soviet leader Leonid Brezhnev in 1974.
Nawrocki has proposed that the Chapter of the Order of the White Eagle meet on June 8 to consider revoking the decoration, which was awarded to Zelensky by Nawrocki's predecessor, Andrzej Duda, in 2023.
Nawrocki said Zelensky's decision had handed Russian propaganda "a great deal of oxygen."
Prime Minister Donald Tusk described the naming decision as "concerning from the point of view of our relations" and said it "unnecessarily raises historical differences to a worrying level".
He also implied that Nawrocki's response was an escalation of a similar kind, warning that if both presidents led a dispute rooted in historical emotion, "the Kremlin would have reason to rejoice."
He later posted on X: "If we quarrel about the past, someone else will win the future."
Poland's foreign ministry said Deputy Minister Marcin Bosacki had summoned Ukrainian Ambassador Vasyl Bodnar to convey Warsaw's disappointment.
Sikorski said he hoped the message, delivered at multiple levels, would be "enough for the Ukrainian side to understand our outrage."
Zelensky named the unit on Wednesday, saying he wanted to "restore the historical traditions of the national army."
The UPA is held responsible for the massacre of tens of thousands of Polish civilians in Volhynia and Eastern Galicia during World War II.
(ał)
Source: PAP