Speaking before a Cabinet meeting in Warsaw, Tusk said reports that the gathering would take place "in the E4 or E5 format" were untrue.
The E4 diplomatic group comprises Poland, Britain, France and Germany. The E5 adds Italy.
The Norwegian government said on Tuesday that US envoys Steve Witkoff and Jared Kushner would hold talks with Ukrainian President Volodymyr Zelensky in Oslo later in the day.
The Reuters news agency reported earlier that representatives of the E4 countries and officials from the EU and NATO would also join the latest round of talks on ending Russia's war in Ukraine.
Tusk called the reports "some kind of misunderstanding."
He said the Oslo meeting would involve Witkoff and Zelensky’s team, with Kushner joining remotely.
He noted that Witkoff was also scheduled to travel to Moscow after the talks in the Norwegian capital.
The meeting in Oslo is being hosted by Norwegian Prime Minister Jonas Gahr Støre, alongside Finland’s President Alexander Stubb, Polish state news agency PAP reported.
Tusk said he was "in constant contact" with both leaders and was being kept informed of the preparations.
He urged caution about what the talks might achieve, saying they should be viewed as further consultations and a test of "whether conditions exist for a ceasefire."
He added that statements and proposals emerging from various capitals were raising both hope and concern.
Tusk called for the West to remain united in its support for Kyiv, both during the war and in any future peace talks.
Poland and Europe, he said, would continue efforts to support Ukraine and reject any demands that could affect their own security.
He told Poles to remain reassured that his government was "following events closely" and that everything was "under control."
(ał/gs)
Source: PAP