The 50-year-old star said it was his character, who narrates the teaser trailer, which was released earlier this month, reported Ace Showbiz.
"I have to be very careful about how I answer these questions. The character... He's been through some stuff," Serkis said.
Serkis was reported to play two characters in the much awaited movie earlier, but he denied the rumours.
"Not true at all. I can say I only play one character," he said.
The actor who is popular for his performances in 'Lord of the Rings' trilogy and 'Dawn of the Planet of the Apes' refused to reveal more information about the movie.