Andre Berto -- Conor McGregor Called Me ... After I KO'd Ortiz (VIDEO)

Andre Berto says he got one helluva phone call after he beat up Victor Ortiz this weekend ... when Conor McGregor dialed him up to congratulate him on the K.O.

In case you missed it, Berto almost took Ortiz's head up with a ferocious uppercut in the 4th round of their Premier Boxing Championships fight at the StubHub Center.

As for McGregor, he and Berto have been friends for a while -- and Berto even advised him to NOT take a rematch with Nate Diaz back when that option was on the table.

But don't count McGregor out ... Berto says the Irish phenom has plans to return to the sport in a big way.