Yes, cluster munition poses unacceptable harm to civilians, because they are a type of weapon that is able to do damage to other things than its target. Because of cluster bombs, an army is able to target more than one small space only. The weapons are too likely to hurt civilians that are near intended targets. Governments can find other ways to wage warfare.
No, cluster bombs do not pose unacceptable harm to civilians, because they can be used with great precision. A government that has no control or discretion is capable of hurting civilians in many ways. The cluster bombs, by themselves, do not pose an unreasonable risk, because they can be targeted. In fact, they allow a government to attack an enemy combatant without hurting many innocent civilians in the process.