Apologize for a misunderstanding

Eugeni: Excuse me. Can I have a word with you?
Xuni: Yes. Is there a problem?
Eugeni: I'm afraid so. Did you know that this is private property?
Xuni: No, I didn't.
Eugeni: Didn't you see the sign?
Xuni: No, I'm afraid not.
Eugeni: Have you been here before to skateboard?
Xuni: No, I live out of town.
Eugeni: Well, if I were you, I'd look for a different place.
Xuni: OK. Sorry about that. I didn't realize.
Eugeni: That's OK. Remember for next time.

KEY PHRASES

Can I have a word with you?

I'm afraid so / not.

If i were you, I'd...

Sorry about that.

I didn't realize.