Strikeforce is currently looking for a replacement to fight Mousasi, but the organization has yet to sign anyone as of Thursday afternoon.
The Kyle-Mousasi fight was scheduled to be a part of April 9's four-fight card, co-headlined by Nick Diaz vs. Paul Daley and Gilbert Melendez vs. Tatsuya Kawajiri.
Kyle (18-8-1, 1 NC) broke his right hand in a December loss to Antonio Silva. The loss snapped Kyle's six-fight undefeated streak.
Mousasi (30-3-1) is 2-0 since losing his light heavyweight title to Muhammed Lawal last April. He hasn't competed for Strikeforce since the loss to "King Mo."
Also scheduled for the April 9 card in San Diego, is a lightweight bout between Shinya Aoki and Lyle Beerbohm.