It's always a bribe. In places without a fully-functional rule of law, it may also be the necessary payment (i.e., the payment of bribes may be expected to conduct business or get through a checkpoint or whatever), but it's still a bribe.

It's actually pretty common for bribes to be requested by the official - the first answer at https://www.quora.com/What-should-I-do-if-the-customs-office... has a description of how this sort of thing usually works.