The Ukrainian said that the his opponent "fought bravely" and praised him for his successful battle with testicular cancer.
"I want to thank my opponent. There are a lot of challengers who talk a lot, but he got in the ring and fought bravely," he told reporters after the fight.
"After the battle he has had against cancer, he deserves respect. He tried everything to hit me. If he had landed one of his big punches, I wouldn't have got up."
Pianeta, who went into the fight unbeaten, admitted that he was "very disappointed and sad" following the sixth-round defeat.