The producer told Entertainment Weekly that the Showtime drama's next run will likely be "smaller" in scale.
"I think all of us on the writing staff would rather not do an impending attack that Carrie (Claire Danes) stops for the third year in a row," Gansa explained.
"Having said that, we haven't found that narrative engine that's going to take us through the third season so I have to reserve judgment. We're looking for something that's smaller, that is sort of a little more [akin to the work of spy author] John LeCarre."
Gansa announced last week that early planning work was underway on the third season of Homeland.
"We know roughly what season three is," he confirmed. "There's some big muscular moves that we know will happen but there's a lot to be filled in still."
Homeland's second season concluded last night on Showtime in the US, with the finale set to air this Sunday on Channel 4 in the UK.
> Homeland recap: The end of an era in 'In Memoriam'
> Homeland Damian Lewis on seven-year contract: 'Brody could still die'
Watch a clip from Homeland below: