At the end of Real's 3-3 draw at Rayo Vallecano, Vinicius made a 'to the Segunda' gesture to taunting fans as he left the pitch.
The Brazil attacker is now being investigated by the LaLiga for his behaviour.
Guti said on El Chiringuito: "I've also had some gestures that I've made... Sometimes you're angry, you've lost or it hasn't been your day and you don't want someone insulting you from the stands. That's it. That's how it is.
"I completely understand Vinicius. It can happen. It's 3-3, he came on and things didn't go well for him... then he had the run-in with the referee, the penalty that wasn't called... And then, if you have to put up with some kind of inappropriate comment from someone, you end up reacting..."
Rayo president Raul Martin Presa has since defended the home support: "For me, the other day the public behaved in a very polite manner. Nobody was insulted, no one was disrespectful. It is an inappropriate gesture, but that is football, and that is what it is. The behaviour of the Vallecas fans was excellent throughout the match."
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