The rapper - whose real name is Nayvadius DeMun Wilburn - took to social media to launch a furious rant against the singer, claiming that she was denying him access to their son, also called Future.
He wrote: "This bitch got control problems... I gotta go through lawyers to see babyfuture...the fuckery for 15k a month. (sic)."
He said: "I jus want babyfuture that's all. I been silent for a year & a half..I ran outta patience
"Get ready for this classic. Handling my business staying focus making music surrounded by real love & family (sic)."
Future - who has four children with four different women - welcomed a son with Ciara in May 2014 but the couple called off their engagement just three months later.
Ciara has now moved on with Russell Wilson and said she "definitely" wants more children with the American footballer.
She previously said: "I definitely want more kids, yes. Russell and I discuss a lot of things ... a lot of good things!"
Asked about the Seattle Seahawks quarterback's relationship with her son, she added: "He is just an amazing guy. Honestly, him being in my life is really sweet ... Life is pretty good, I can say that."