"It's very disappointing," said Robinson, whose side defeated their Irish opponents in the same fixture during last season's competition.
"We certainly have to understand how to tackle. The first-half tackles that we missed were poor."
Edinburgh's home form in the 2007/08 Heineken Cup was impressive, with a narrow loss to Toulouse followed by wins over Leinster and Leicester, but they started this year's campaign poorly during the opening half on Saturday afternoon.
Michael Chieka's Magners League Champions had opened up a 24-3 lead inside the opening 38 minutes, from which there was no way back for Edinburgh.
"We have to understand that you've got to start well and from there, it's a basis to go and win a game.
"Leinster hadn't really created anything, they just broke our line and scored four tries just from unstructured play.
"Too often we say, 'if only this or if only that.' We can't keep doing that. It's not good enough."