People roam around a used-books street market in downtown Lviv, Western Ukraine, Saturday, March 19, 2022. AP
"China can be the global security system's important element if it makes a right decision to support the civilised countries' coalition and condemn Russian barbarism," presidential aide Mikhailo Podolyak wrote on Twitter.
China has stayed out of the international outcry against Russia's actions in Ukraine, refusing to condemn President Vladimir Putin's invasion.
US President Joe Biden told Chinese leader X Jinping in a call Friday that any backing for Russia in its war in Ukraine would be costly.
The White House said that Biden described to Xi "the implications and consequences if China provides material support to Russia as it conducts brutal attacks against Ukrainian cities and civilians."
It did not give Xi's response.
Xi and Putin met last month at the Winter Olympics in Beijing, shortly before Putin launched his invasion of Ukraine.