Pervez Musharraf, the Pakistan president, whose opponents dominate parliament, accused Baitullah Mehsud, a Pakistani Taliban leader, for the murder.
Mehsud has denied any involvement.
Some Pakistanis blame intelligence agency operatives for the murder, which Musharraf denies.
Amrohvi said that the resolution would be sent to the foreign ministry in order that it could contact the UN.
'Identify culprits'
Farooq Naik, the law minister, said the investigation should "probe and identify the culprits, perpetrators, organisers and financiers behind this heinous crime and bring them to justice".
Musharraf has opposed a UN inquiry. He did allow the British police to investigate what killed Bhutto.
They found she died after hitting her head against the vehicle she was travelling in during the attack.
In February's elections Musharraf's power dwindled as a new government was formed by his opponents - led by the PPP.
Police have arrested at least four people, believed to be linked to the Taliban, over the killing.