The leading stars - who play Edward Cullen, Bella Swan and Jacob Black in the vampire movie franchise - will instead record special video messages that will play to fans at the event in London's Leicester Square on July 1.
A statement read: "Kristen Stewart, Robert Pattinson and Taylor Lautner will not be far away with specially record video messages for their UK fans."
Robert, 24, is unable to attend due to filming commitments on the Francis Lawrence-directed drama 'Water for Elephants', although it is not yet clear with Kristen or Taylor will be unable to visit for the premiere.
Kellan - who plays Robert Pattinson's on-screen brother Emmett in the adaptation of Stephenie Meyer's novel - recently claimed the third film in the movie franchise would be one for the boys.
He said: "The guys are going to bring their girlfriends to this one, mark my words.
"There's a lot of fighting, a lot of cool stunts. It's a little darker. The stuff I've seen so far is amazing. Amazing. The music is great."
'The Twilight Saga: Eclipse' will be released in UK cinemas on July 9.