Once again, Kobe Bryant is under attack from a former Lakers teammate -- this time, it's Dennis Rodman throwing shade ... and TMZ Sports has the footage.

Rodman -- who played with Kobe during the 98-99 season -- was at the W Hotel in Hollywood on November 3rd (singing with the jazz band) ... when he grabbed he mic and put Kobe on blast.

"Kobe Bryant ... one thing -- f**k him," Rodman said ... "F**k him. F**k him. I'll say it again, f**k him."

It's unclear why Rodman has an axe to grind with the Mamba ... but he ain't the first to beef with Bryant.