The first season of the Fox sci-fi drama will draw to a close with a double-bill on December 19.
O'Mara, who plays Jim Shannon, wrote on Twitter: "Decision to pick up Terra Nova for S2 deferred to New Year by [Fox]."
However, the actor continued: "Everyone involved remains confident and optimistic."
Terra Nova actress Shelley Conn, who plays O'Mara's on-screen wife Elisabeth, recently told Digital Spy that the show's future "looks positive".
"We're so invested that it would break my heart if we didn't get another chance at this," she said. "I just think everybody's worked so hard and we've created something that deserves to be continued."
Executive producers René Echevarria and Brannon Braga also confirmed in October that the first season of Terra Nova will end on a cliffhanger.
The show returns to Fox on Monday at 8/7c. Sky1 airs the series in the UK.
> Terra Nova: 'Now You See Me' recap
Watch a preview clip from the next Terra Nova below: