Piven, 52, is currently starring on the network's Wisdom of the Crowd. He was accused of groping Bellmar on the set of HBO's hit series Entourage.
"We are aware of the media reports and are looking into the matter," the statement read, according to The Hollywood Reporter.
Bellamar raised the allegations in a series of tweets.
Bellamar's tweets did not specify if the alleged incident(s) took place on the set of the Entourage TV show or during the subsequent movie released in 2015. As for the TV series, it ran for eight seasons from 2004-2011.
Her acting credits do not include an appearance on Entourage, but she has been involved in Beverly Hills Nannies and Millionaire Matchmaker.
Piven is one of several Hollywood superstars that have been accused of sexual misconduct recently. Just this weekend, Star Trek actor Anthony Rapp alleged that Oscar winner Kevin Spacey sexually harassed him when he was just 14-years-old.