"I am so disappointed that my message has been corrupted: these pictures divided people when they were meant to unite. That's why I deleted them.
"I sincerely apologise to all the people I have offended. I truly had only good intentions."
Yastremska scrubbed the series of pictures from her accounts, in which she is topless and half her body is black. She accompanied the posts with the caption: "Equality."
The world No. 25 was called out by US Open and Australian Open champion Naomi Osaka, who commented on her Instagram post saying "Girl I know you didn't just do blackface", with a skull emoji.
Yastremska responded with a prayer emoji.
Last month world No. 73 Taylor Townsend spoke out about her experiences of racism in the sport and claimed black players are often mistaken for each other.
"Even in the tennis world it is not a united place," she told the WTA. "We lose our identity of who we are because there can only be one.
"I've had people argue with me to tell me that I'm Coco Gauff. I'm not Coco Gauff but all of us look the same, all of us are built the same, everybody sees a black person and they assume it's Venus or Serena (Williams) or Sloane (Stephens).
"Even from the aspect you walk through and nobody stops you, and I'm walking through and somebody has to check my bag, check my credential, check my coach's bag, check my coach's credential.
"It's extra security, extra precautions that need to be taken to make sure I belong."
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Tennis hasn't done itself any favours during lockdown as a series of controversies have cast doubt over players' ability to follow the rules while COVID-19 causes havoc around the world.
Novak Djokovic and several other stars tested positive to coronavirus after participating in the Serbian's disastrous Adria Tour, which featured no social distancing whatsoever and allowed crowds, volunteers and ballkids to mingle freely during the tournament and at promotional events.
German Alexander Zverev, who took part in the Adria Tour, was also filmed partying shortly after vowing to follow medical advice.