Most just don't answer and with these I never bother. But then there are girls who seem interested, ask questions and write long messages. Some of these stop when you ask them out for coffee/beer, few even agreed on meeting but went silent about the timings.

How to respond or should I forget them?

Needy would be like: why don't you answer? So it is a no. What about: I understand you are afraid but I don't bite or something similar?