The 31-year-old reality star has two-year-old Dream with his former partner Chyna, and is believed to be angry after she spent the weekend in Honolulu, Hawaii and planned on having Dream stay with a nanny, rather than letting Rob keep her for longer as per their custody agreement.
A source told People magazine: "Chyna planned on having Dream stay with a nanny in LA while she was in Hawaii. Rob is mad because if either parent is out of town, the other parent is supposed to have the option to keep Dream longer.
"Rob doesn’t want Dream to stay alone with a nanny while Chyna parties in Hawaii. This is what he is mad about. She needs to tell him when she won’t be in LA so Rob can keep Dream longer. Rob is getting his lawyer involved."
Rob’s alleged anger comes after police recently visited the home of Blac Chyna – who also has son King Cairo, six, with ex-partner Tyga – when an anonymous call was placed alleging she was too drunk to look after her brood.
Recently, Chyna’s lawyer Lisa Bloom has spoken out on the situation, saying the children are doing fine and were "never in any danger".
She said: "Chyna’s children, King Cairo and Dream Renée, are both healthy and doing very well. They were never in any danger and any reports to the contrary are entirely false.
"I remind the public that anyone who submits a knowingly false report to Child Protective Services may be subject to criminal and civil liability."
It was previously revealed police had called to Chyna’s home after receiving an anonymous call alleging the ‘Rob + Chyna’ star was intoxicated and neglecting her children.
However, when cops got to the house, they found no one was drunk and not only were her children being properly looked after, there was also a nanny in attendance at the property.