The video from the Jundollah (God's Soldiers) showed the worried-looking hostages flanked by armed masked rebels and a leader of the group that the television said demanded the release of five imprisoned comrades.
A group from the Baluchi ethnic minority last week claimed responsibility for an attack that killed 22 people in a remote region in southeastern Iran and said it had taken seven hostages.
The video showed what appeared to be identification cards of the hostages, who the group said belonged to Iran's army, security forces and Red Crescent aid organisation.
The group has kidnapped Iranian soldiers in the past to try to force the release of detained members.
The attack was in impoverished areas on the borders with Pakistan and Afghanistan, the scene of sporadic unrest among Iran's Baluchi minority, most of them Sunnis, and frequent police clashes with armed drug smugglers.
Iran's police chief blamed the attack on bandits and accused British forces in Iraq of helping them.
Iran also blames Britain for unrest in its restive and mainly Arab southwestern oil province of Khuzestan, across the border from southern Iraq where British troops are stationed. Britain denies supporting the ethnic Arab rebels.