Polish President Andrzej Duda urged his Ukrainian counterpart President Volodymyr Zelenskyy on Friday to keep up calm and constructive cooperation with President Donald Trump, following Trump's criticism of him this week.

"I suggested to President Zelenskyy to remain committed to the course of calm and constructive cooperation with Donald Trump," Duda wrote on the social media platform X.

"I have no doubt that President Trump is guided by a deep sense of responsibility for global stability and peace," he added.

Duda, whose term in office expires in 2025, was one of Trump's preferred international partners during his 2017-2021 presidency, and they have described themselves as friends.

Trump labeled Zelenskyy as a "dictator" on Wednesday and warned he had to move quickly to secure peace with Russia or risk losing his country, deepening a feud between the two leaders that has alarmed European officials.

Zelenskyy responded by saying Trump was trapped in a "disinformation bubble" but later toned down his statements and said he was hoping for American pragmatism.

He said on Friday he had discussed in a call with Duda the dialogue with the U.S. team led by Ukraine envoy Keith Kellogg.

"It is important that the United States stand with us. A strong and lasting peace can only be achieved through unity," Zelenskyy said on X.