In the letter, the National Counter Terrorism Authority said the foreign spy agency had paid Rs 80 million to two activists of a banned outfit for the assassination of Saeed.
It asked the Punjab home department to ensure foolproof security for the Jamat-ud-Dawah (JuD) chief.
Saeed has been under house arrest in Lahore since January 30 under the Anti-Terrorism Act 1997.
The home department last month had extended his detention for another 30 days (till November 26) under public safety law.
The department's notification had said, "There is apprehension that Saeed shall create a law and order situation upon release".
The JuD has already been declared as a foreign terrorist organisation by the US in June 2014. The JuD chief carries a reward of USD 10 million announced by the US for his role in terror activities.