You are the neighbour 1. Explain that you can't. You're busy right now.
I'm sorry, I can't. I'm busy right now.
You are the neighbour 2.Explain that you are happy to meet your neighbour too. Invite your neighbour for a cup of tea.
Nice to meet you, too. Would you like a cup of tea?
You are the neighbour 1. Say that you are happy to meet your neighbour.
Nice to meet you. Pleased to meet you.