Buyer is leaving messages in Portuguese which I don’t speak.

[tn57roots]

A prospective buyer is in another country. My listing states only shipping in U.S.  He sent me questions in what I believe is Portuguese since his address is in Portugal. I asked him to have his message translated but he did not. I believe he asked about shipping overseas so I sent a message stating I only ship within US. Now he is the high bidder and wants me to send an invoice.  This is only the 3rd thing I have sold on eBay, I have purchased a lot though.  I don’t want to do anything against the rules but I am not going to deal with shipping overseas.  And I don’t want to end up with a bunch of negative feedback. Is it okay to cancel the transaction or just not send him an invoice?  Thanks for any help.