Polish President Andrzej Duda said on Saturday that Poland saw a need to maintain Western sanctions against Russia over its 2014 annexation of the Crimea region from Ukraine.
He also said Ukraine should have closer relations with the European Union and the NATO military alliance.
Ukraine must regain the full territorial integrity it enjoyed before 2014 and reclaim the occupied territories of Crimea as well as the far-eastern Donetsk and Luhansk regions, Duda added.
The West imposed sanctions after Russia annexed the Crimean peninsula from Ukraine in 2014 in retaliation for Kiev ousting its pro-Russian president the same year; Moscow also backs the pro-Russian separatists in Ukraine's east.
Any possible changes in sanctions should go in the direction of intensifying rather than lifting them, Zelensky said via interpreter.
The Ukrainian president also criticized the Russo-German Nord Stream 2 natural gas project, calling it a threat to the entire continent.
Nord Stream 2, currently under construction, will increase the amount of natural gas transferred from Russia directly to Germany, allowing the Russian supplier to bypass transit countries such as Ukraine, Belarus and Poland.
US President Donald Trump has also criticized the pipeline for making Germany too dependent on Russia for its energy needs.
Zelensky arrived in Warsaw for a state visit on Saturday. During the talks with his Polish counterpart the two sides discussed, among other issues, transport, infrastructure and security in the region.
Later on Saturday Zelensky is scheduled to meet Polish Prime Minister Mateusz Morawiecki.
The Ukrainian president, who assumed office in May, is also due to participate in the Sunday commemoration of the 80th anniversary of the outbreak of World War II.
U.S. President Donald Trump has said it would be appropriate to have Russia rejoin what used to be the G8 group of advanced economies, from which Russia was excluded in 2014 over Crimea's annexation and for backing pro-Russian rebels in Ukraine.
But the European Council president on Aug. 24 rebuffed Trump's suggestion, saying there were even more reasons than before for keeping Moscow out.
