The Commonwealth conference, to be held in Islamabad on September 30, has been cancelled because Indian lawmakers from Kashmir planned to attend, said Pakistani parliamentary speaker Ayaz Sadiq.
Pakistan "saw an opportunity to raise the Kashmir issue" by refusing to host the conference, Mr Sadiq said.
"When it is clear that we have fought wars over this, brought resolutions in the United Nations, then how can we abandon our point of view (on Kashmir) now?" he said.
It is unclear if the parliamentary conference is cancelled or will be held elsewhere. The Commonwealth Parliamentary Association links legislators in former British colonies.
On Sunday, the National Security Advisors of India and Pakistan, Ajit Doval and Sartaj Aziz, are to meet in Delhi. However, the Pakistani High Commission in New Delhi has invited Kashmiri separatists to dinner on Sunday evening. Indian officials have said they will "prevent" the separatists from attending the reception for Mr Aziz.
Pakistan says it will not call off the meeting with the separatists. The extreme positions taken by both sides have led to speculation about whether the NSA talks will continue. Indian sources say they will not succumb to a series of provocations from Pakistan which wants Delhi to cancel the dialogue.
A year ago, India cancelled talks between the two nations' foreign secretaries after a similar meeting with Kashmiri separatists.
Ties warmed last month, after Prime Minister Narendra Modi met with Pakistani premier on the sidelines of a summit in Russia and agreed to resume high-level talks.