Ohanian slammed Tiriac on social media, accusing him of being racist and sexist following his comments made on Romanian TV.
"At this age and the weight she is now, she does not move as easily as she did 15 years ago," Tiriac said.
"Serena was a sensational player. If she had a little decency, she would retire."
Tiriac is no stranger to making comments on Williams' weight after a similar comment in 2018, comments which the 23-time Grand Slam winner labelled "ignorant" and "sexist".