The vessel, captured during the initial occupation of Crimea, has been a symbol of Russian military aggression against Ukraine.
"Unfortunately, a decision was made to inflict fire damage on this unit," Pletenchuk said, as quoted by Ukrinform news agency.
He added: "We had no choice. We used a Ukrainian Neptune missile, and the damage was inflicted."
The Konstantin Olshansky was originally constructed in the Polish Baltic port city of Gdańsk. It fell into Russian hands in Crimea in 2014.
The ship, which had remained in Sevastopol Bay being dismantled for parts, was targeted by Ukraine after indications that Russia intended to recommission it for use against Ukrainian forces.
Since the beginning of the full-scale aggression, the Ukrainian army has destroyed or damaged nearly 30 Russian ships of various types, Ukrinform reported.
(jh/gs)
Source: PAP, IAR, Ukrinform