Speaking on Thursday, Medvedev, who won the US Open last year, addressed the situation in his home country after winning his match in Mexico, saying he is "all for peace."
"In this moment, you understand that tennis sometimes is not that important," he said.
He continued, "By being a tennis player, I want to promote peace all over the world. We play in so many different countries. I've been in so many countries as a junior and as a pro. It's just not easy to hear all this news."
On Friday, Andrey Rublev also advocated for peace, writing "No war please" on the camera after his win. Writing on the lens is a common practice after tennis matches.
The day before, on Thursday, the No. 7 player in the world explained his stance in an interview after his match.
"In these moments you realize that my match is not important. It's not about my match, how it affects me. Because what's happening is much more terrible," Rublev said. "You realize how important it is to have peace in the world and to respect each other no matter what and to be united.... We should take care of our earth and of each other. This is the most important thing."
Russian and Ukrainian athletes across other sports have spoken up in recent days, too.
Fyodor Smolov, a Russian soccer player who has been capped 45 times by the national team, posted a black screen to Instagram on Thursday, with the caption "No to war," along with emojis of a broken heart and a Ukrainian flag.
All this comes after Russia's assault on Ukraine, which began on Thursday and has spread across the country. Russian forces have attacked by land, sea and air, and are currently battling for control of Ukraine's capital, Kyiv.