I saw this film when it first came out. Which kind of reveals my age. Then I saw it later on television in the late 1960's. My recollection was that those famous words were spoken by Klatu to the character played by Patricia Neal and again by Patricia Neal to the giant robot Gort.
Have to admit my memory was fuzzy on who the female lead was but I recall the scene vividly. The terrified woman looking up at the robot as he was about to vaporize her with his particle beam ...
So I went to Google and looked up the movie, 'The Day the Earth Stood Still.'
I found many *.wav files which include both the 'Klatu, barata, nicto' comments from the film including the command to Gort to not destroy the earth, made by Patricia Neal's character 'Helen.'