U.S. President Joe Biden on Friday warned his Chinese counterpart Xi Jinping of the "consequences" Beijing will face if it steps in to support Russia's invasion of Ukraine, while Xi expressed hope for an early cease-fire but apparently avoided characterizing Russia as the aggressor.

The video call, the first talks between the two leaders since Russia launched its invasion of Ukraine on Feb. 24, took place amid growing concerns in Washington that Beijing is considering directly assisting Moscow with military equipment to use in the conflict.

U.S. officials were unclear as to whether China offered any guarantees that would address their concerns.

U.S. President Joe Biden (L, Getty) and Chinese President Xi Jinping (Kyodo). 

White House Press Secretary Jen Psaki told a press conference later in the day, "Obviously actions are a key part of what we'll be watching."

"China has to make a decision for themselves about where they want to stand and how they want the history books to look at them and view their actions," she said.

During the two-hour talks, Biden described the "implications and consequences if China provides material support to Russia as it conducts brutal attacks against Ukrainian cities and civilians," the White House said in a press release.

Biden underscored his support for a diplomatic resolution to the crisis, while the two leaders agreed on the importance of maintaining open lines of communication and working to manage the competition between the world's largest and second-largest economies.

According to the Chinese Foreign Ministry, Xi said "China does not want to see the situation in Ukraine come to this" and the "pressing priority is to keep the dialogue and negotiation going, avoid civilian casualties, prevent a humanitarian crisis, and cease hostilities as soon as possible."

Xi, meanwhile, indicated his opposition to imposing sanctions on Russia, as the United States and its allies and partners continue to roll out punishing measures for what they view as Moscow's unjustified aggression.

"Sweeping and indiscriminate sanctions would only make the people suffer," Xi told Biden, expressing concerns that a further escalation could "trigger serious crises" in the global economy, affecting trade, energy and food, and supply chains.

The "vast majority" of the discussion was spent on Russia's invasion of Ukraine as well as the issue of Taiwan, which was raised by the Chinese side, Psaki said.

Biden reiterated that U.S. policy on Taiwan has not changed, and emphasized that Washington continues to oppose any unilateral changes to the status quo, in a veiled warning to Beijing which is seeking to bring the self-ruled island back into its fold, by force if necessary.

Xi was quoted as saying that some people in the United States have sent the "wrong signal" to so-called Taiwan independence forces, and warned that "mishandling of the Taiwan question will have a disruptive impact on the bilateral ties."

Amid the growing economic and military rivalry between their two countries, Biden was quoted as saying that the United States does not seek a new Cold War with China.

Xi and Biden agreed that their discussion was "constructive" and decided to "promptly follow up and take concrete actions to put China-U.S. relations back on the track of steady development," according to the Chinese ministry.

Russia began the military campaign against Ukraine after asserting that its security was under threat from the North Atlantic Treaty Organization's eastward expansion and the possibility of Ukraine joining the security alliance.

But its invasion has met stiff resistance from Ukrainian forces, with the West rallying behind Kyiv to provide security and financial assistance.

Xi said China is ready to provide further humanitarian assistance to Ukraine and other affected countries, while calling on the United States and NATO to engage in dialogue with Russia to "address the crux of the Ukraine crisis and ease the security concerns of both Russia and Ukraine," according to the Chinese ministry.

A few weeks before the start of the attack, China and Russia declared that their friendship has "no limits" in a joint statement following a meeting between Xi and Russian President Vladimir Putin.

When the U.N. General Assembly adopted a nonbinding resolution censuring Russia in March, China was among the 35 countries that abstained from voting.