The 38-year-old striker announced his decision yesterday, saying he wants focus on winning a championship in the second-tier league. He signed with the Cosmos last December.
Raul calls his move "not an easy one, but I believe it is the right time."
He says he will decide in the coming months what he wants to do next.
Cosmos coach Giovanni Savarese describes Raul as "one of the world's most iconic players," lauding his "knowledge, passion, professionalism and commitment."
Raul spent 16 years with Real Madrid. He led the team to four Spanish league titles, four Spanish Super Cups and three UEFA Champions League titles. He left in 2010 as the team's career goal-scorer. He later played for Schalke 04 in Germany and Al-Sadd Sports Club of Qatar.