Shatner – who played Captain Kirk in Star Trek - told Movie Fanatic it was wrong for Abrams for take on the Star Wars franchise while he is still heavily involved in Star Trek into Darkness.
"He's being a pig," Shatner quipped, adding: "He's collecting the two franchises and holding them close to his vest."
He continued: "He's probably the most talented director of that ilk that we have, but he's gone too far this time."
Shatner went on to insist that his criticism of Abrams comes from a place of friendship.
"I think of him as a buddy of mine, I've taken him out for sushi. I think it's time for JJ and I to have another sushi and let me put him straight," the 81-year-old actor declared.
His Star Trek co-star George Takei expressed opposite feelings about Abrams directing Star Wars Episode 7, saying last week that he's "all for" the filmmaker overseeing both franchises.
Shatner previously caused controversy in 2011 when he suggested that Star Trek is better than Star Wars because it had much greater social relevance.
Star Trek into Darkness - which stars Chris Pine as Kirk and Zachary Quinto as Spock – opens on May 17 in the US and the UK.
Watch a trailer for the film below:
Photo Gallery: The 'Star Wars' series