The Spaniard spent two years with the Reds after signing from Espanyol in the summer of 2008, and scored five goals in his 56 appearances.
Riera announced the decision to end his career on Tuesday night, saying: “[It is the] right time to say bye as a player.
“Thanks to the clubs and the supporters that have been along this way with me from 2001 till today. Proud and thankful for the way we have been together during 17 years.
“Now time to look forward and impatient for my new step!”