The attacks left 173 people dead
Pakistan says a dossier provided by India as evidence that links the Mumbai (Bombay) attacks to elements in Pakistan is merely "information".
PM Yousuf Raza Gilani said Pakistan was still examining the dossier.
Separately, India's interior minister accused Pakistan of doing nothing and said ties could "snap" if it did not help in probing the attacks.
Relations between India and Pakistan have deteriorated sharply since the November attacks which left 173 dead.
Earlier this month, India handed over to Pakistan what it described as evidence of the involvement of elements in Pakistan to the deadly attacks.
The evidence is said to include the interrogation of the surviving gunman, details of phone conversations between the attackers and weapons information.
Mr Gilani said he hoped India would agree to a joint investigation into the attacks.
"All that has been received formally from India is some information," Mr Gilani told the National Assembly.
"I say 'information' because these are not evidence. This needs to be carefully examined. Serious, sustained and pragmatic co-operation is the way forward."
Pakistan has said it will punish any of its citizens if "credible" evidence is found of their involvement in the attacks.
Asked what Pakistan was doing to co-operate with the investigation, Indian Interior Minister Palaniappan Chidambaram told the UK's Times newspaper: "Zero. What have they provided? Nothing.
"There are many, many links between India and Pakistan, and if Pakistan does not co-operate and does not help to bring the perpetrators to heel, those ties will become weaker and weaker and one day snap," he said.
UK Foreign Secretary David Miliband said on Tuesday that Pakistan had a primary responsibility to act against those who carried out the Mumbai attacks.
Mr Miliband said he did not believe the attacks had been "directed by the Pakistani state", but links could clearly be traced to Pakistan-based group Lashkar-e-Taiba.
India says all 10 gunmen were from Lashkar-e-Taiba.
Pakistan admitted last week that the only surviving gunman - Mohammed Ajmal Amir Qasab - was a Pakistani citizen.