His comments come as the Russian Defense Ministry announced that the Russian patrol ships Sergey Kotov and Vasily Bykov were attacked by three unmanned sea boats in the Black Sea overnight on August 1.
The ministry subsequently claimed that civilian ships came under fire in the engagement.
"Undoubtedly, such statements by Russian officials are fictitious and do not contain even a shred of truth," Podolyak said.
"Ukraine has not attacked, is not attacking, and will not attack civilian vessels, nor any other civilian objects."
According to naval tracking imagery, three civilian vessels originated in Israel, Greece, and Turkey/Georgia successfully made it to Ukrainian grain terminals in the Danube Delta on July 30.
Ukrainian news outlet Militarnyi reported that the first ship to defy Russia’s warning sailed under an Israeli flag, and entered the Ukrainian Danube estuary on July 25, followed by four more ships.
Russia terminated its participation in the Black Sea Grain Initiative on July 17, saying its decision was due to explosions on the illegally built Crimea Bridge. The aggressor country subsequently threatened vessels bound for Ukrainian ports.
On the same day, Ukraine's President Volodymyr Zelenskyy proposed to extend the grain deal without Russian participation, jointly with Turkey and the UN.
The Black Sea grain deal had allowed secure Ukrainian grain exports starting from August 1, 2022. However, Russia kept threatening and hindering the initiative.
Russia announced on July 19 that it will consider all ships sailing to Ukrainian ports to be "military targets."
In response, Ukraine's Defense Ministry warned that it would consider all vessels heading to Russian ports in the Black Sea, as well as to ports in the temporarily occupied territories, as "carrying military cargo with all the corresponding risks."
A spokesperson for the Southern Ukraine Defense Forces, Natalia Humeniuk, said they saw indications that Russia is gearing up to blockade the Black Sea.
She also warned about possible Russian false-flag attacks against third parties' vessels in the Black Sea. The US State Department also issues a similar warning.