Bobby Brown -- Fighting Whitney Houston's Family to See Bobbi Kristina

Bobby Brown still hasn't seen his daughter -- THREE days after Whitney Houston's death -- and he thinks Whitney's family ... specifically, Cissy Houston, is throwing up the road block.

Sources close to Bobby tell us he hasn't connected with Bobbi Kristina since arriving in L.A. Sunday night -- despite placing several phone calls and making an attempt to physically see her ... early this morning.

We're told Brown was turned away by Whitney's family and friends ... who are caring for BK at a home in the Los Angeles area.

According to our sources, Bobby is angry and frustrated because he only came to L.A. to care for 18-year-old Bobbi Kristina after she was hospitalized twice.

As for why he's blaming Whitney's mom for the freeze out -- we're told Brown thinks Cissy has hated him for years.

In-laws.