In both attacks the suspect pursued the women after they has just passed him in the opposite direction, turned around and grabbed or slapped them on the buttocks, police said.
The suspect then fled from the victims, who were not injured in either incident, police said.
The first attack happened at about 7:30 p.m. on Escalona Drive near Oliver Street and the second on Western Drive near Echo Street about 30 minutes later.
The victim of the second attack told police she and her boyfriend returned to the area, found the suspect in the vicinity and confronted him.
The suspect then apologized to them before fleeing, police said.
Police produced a pair of sketches based on separate descriptions from the second victim and her boyfriend.
The man is described as Hispanic, in his late teens to early 20s, from 5 feet 6 to 5 feet 7 inches tall with a slender build, small frame and dark hair.
Anyone with information about the suspect is urged to notify the Santa Cruz Police Department's investigative unit at (831) 420-5820.