It was announced last month that UK Sport will be unable to provide funding for Team GB ahead of the Rio 2016 Olympic Games.
"We all heard about the 'legacy' that London 2012 was going to bring to sport in the UK and I refuse to sit back and let that legacy be completely demolished for basketball," Deng wrote in a letter to Cameron, according to The Guardian.
"I, along with other people involved in the game, have put too much in and care too greatly to let this happen. The sport of basketball is a pathway, a pathway that teaches so many valuable lessons on and off the court, how are we supposed to motivate these kids to carry along their journey when there's now nothing at the end? No Team GB, no Olympic dream, no goal."
The 27-year-old. who plays for the Chicago Bulls in the NBA, represented Britain in the London 2012 Games last summer.