Rafael Nadal has described Wimbledon's ban on Russian and Belarusian players as "very unfair" as the ATP considers its response.
Wimbledon officials reiterated their position last week, saying that a directive from the UK government regarding the invasion of Ukraine had left them with no viable alternative but to refuse entries from players from the two countries.
There has been some support for Wimbledon's position, especially from Ukrainians within tennis, but the reaction has been largely negative, with the ATP and WTA both deciding whether to impose penalties.
Speaking ahead of his return to action at the Madrid Open, Nadal told reporters in the Spanish capital: "I think it's very unfair (on) my Russian tennis mates, my colleagues. It's not their fault what's happening in this moment with the war."
Action against Wimbledon and the preceding grass-court tournaments run by the Lawn Tennis Association could include the removal of ranking points.
Nadal, who is a member of the ATP Player Council, added: "The 2,000 points, whenever we go to the grand slams, they are really important and we have to go to those tournaments. So we will have to see the measures that we take.
"At the end of the day, what happens in our game, it doesn't have any importance when we can see so many people dying and suffering and seeing the bad situation they are having in Ukraine."
Nadal is playing his first tournament in six weeks after suffering a stress fracture of a rib at Indian Wells in March.
His loss to Taylor Fritz in the final, when he was clearly physically hampered, ended his 20-match winning streak to start the season.
Nadal is playing catch-up to reach peak fitness in the time for the French Open, and said: "Talking about the injury, I'm recovered, I feel good. Talking about my tennis game and preparations, well, it's a completely different story.
"Anyone who has broken a rib knows how limiting it is, very painful, especially the first weeks. I wasn't able to do anything without a lot of difficulties, even to fall asleep because of the pain.
"I have improved compared to when I came here but I still have up and downs because it's been a long time without being in these kind of situations and it's going to be a difficult week, for sure."
At the BMW Open in Munich, Dane Holger Rune, who turned 19 on Friday, won his first ATP Tour title when opponent Botic Van De Zandschulp retired with injury after just seven games.