I've noticed something really interesting that is true of Hollywood actresses to this day. Petite actresses who get good, versatile roles usually have something in common...they started their careers as children or a teenager. Take Natalie Wood (5' even, according to IMDB), for example. Her best known role as a kid was Susan Walker in original version of Miracle on 34th Street (just to note: Mara Wilson, who played the same role in the 1994 version is also petite, at 5'4" according to IMDB. But she could be much taller, since her last role, according to IMDB was in 2000 when she was 13 years old.) Elizabeth Taylor is 5'2". While she is most known to younger people, at least, for her grown-up roles like Cleopatra or Maggie the Cat, she too, started out as a kid in roles such as Velvet Brown (National Velvet) and the tragic Helen Burns (Jane Eyre, a role she wasn't credited for.) Today, there are actresses like Scarlett Johansson, 5'4" (kid/teen roles include: Kate Armstrong in Just Cause and of course, Grace MacLean in The Horse Whisperer), Christina Ricci, 5'1" (major childhood roles include: Wednesday Addams (The Addams Family and Addams Family Values) and Kate Flax in Mermaids), Natalie Portman, 5'3" (first full length role on IMDB was Léon in 1994) and Reese Witherspoon, who was 14 or 15 when she landed her first role in The Man on the Moon in 1991.
As for petite actresses who start at an older age (say, 16 or older)? I don't know if there really are that many outside of actresses known primarily for their roles on television. Can you name any?