"What I said after the match has led to reactions," the 23-year-old writes on Instagram.
“For me, it was a conscious choice to remind people of what Ukraine and its people are going through.”
After Sunday's final loss to world number one Sabalenka, the 20th-ranked Kostyuk said that she plays every day with a broken heart and that thousands of people in Ukraine have no hot water or the ability to turn on lights due to power outages.
"It's minus 20 degrees outside and it's incredibly painful to live in this reality every day," Kostyuk said.
Several Ukrainian players on the world tennis tour have refused to shake hands with opponents from Russia and Belarus in matches since Russia began its full-scale war of invasion in Ukraine in February 2022.
Both Sabalenka and Kostyuk are playing in the year's first Grand Slam tournament, the Australian Open, which starts on Sunday.
