The Greeks never had a single "scale" in the modern sense which had twelve pitches, or seven for that matter. However:

"Unique to the Greek system were the concepts of *tetrachord* and *genus.* A tetrachord (literally 'four strings') comprised four notes spanning a perfect fourth... Since most melodies exceeded a fourth, theorists combined tetrachords over a larger range... Cleonides noted that in the diatonic genus, the three main consonances of perfect fourth, perfect fifth, and octave were subdivided into tones and semitones in only a limited number of ways, which he called species...

"The seven species of octave... are combinations of the species of fourth and fifth, a division of the octave that became important in medieval and Renaissance theory. Cleonides identified the species by what 'the ancients' supposedly called them... Later writers, including Aristoxenus, Cleonides, and Aristides Quintilianus, used the same names for up to fifteen different *tonoi*, defining a *tonos* as a scale or set of pitches within a specific range or region of the voice. These essentially involve transposing the system of tones up or down by some number of semitones. Like *harmoniai*, tonoi were associated with character and mood, the higher tonoi being energetic and the lower tonoi sedate."

(A History of Western Music, Burkholder, 9th Edition, 2014, pp. 15-17)