The terror attacks in November left 166 people dead and many more injured. Pakistani terrorist Mohammed Ajmal Amir Kasab was caught alive and was tried in a court before being hanged in a jail in India.
"Besides tarnishing Pakistan's image, the attacks also did an irreparable damage to the Kashmir cause," the Dawn quoted Mr Khan as saying.
He was addressing a gathering at the Kashmir Day event held at the Pakistan Embassy in Washington on Sunday, the report said, adding that India's blaming of Pakistan for the attacks did hurt Islamabad's image in the world capitals.
Touqir Hussain, another senior former Pakistani diplomat, who now teaches diplomacy at the Georgetown University, emphasised the need to provide political and moral support to the Kashmiri struggle.
Mr Hussain also referred to a recent statement by America's UN envoy Nikki Haley in which she said the Washington had asked India to keep an eye on Pakistan.
Mr Hussain said that Ms Haley was trying to diminish Pakistan's influence to help India suppress the Kashmiri struggle.
Pakistan's Ambassador to the US Aizaz Chaudhary alleged that the Indian government was using brutal violence to suppress the Kashmiri freedom movement.