If, during your declare attackers step, a creature you control is tapped or is affected by a spell or ability that says it can't attack, then it doesn't attack. If there's a cost associated with having a creature attack, you aren't forced to pay that cost, so it doesn't have to attack in that case either.

Hellraiser Goblin's ability also affects itself. If it enters before combat, it will have to attack that combat if able.