Barcelona beat their Catalan rivals 2-0 in the second leg of their round-of-16 tie in a match which saw seven yellow cards given out.
The return leg was a much tamer affair compared to the first instalment between the two rivals, in which Espanyol had two men sent off in a 4-1 loss.
However, after Gonzalez had fouled Messi in the second leg, the two exchanged insults and laughed about it.
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"Leo was criticising me for some things, and I some others," he told reporters. "I asked him if he thinks I will hurt him, and he said yes.
"He told me that I was bad, and I told him he was short. But both accepted it, laughed, and left it at that.
"There's no need to make a big deal of anything. What happens on the pitch stays there and that's it.
"The best thing about these derbies is the healthy rivalry we have."