Gilani added that the Pakistan Government would now monitor these activities.
Gilani said that Pakistan was committed to peace in the region, but if war is thrust on the country, "we will give a befitting response ... the nation, the army and the political leadership is united, and we can defend our national sovereignty."
"We condemn terrorism wherever it is ... terrorists have no principles, religion, faith, boundaries or scruples," the Daily Times quoted Gilani, as saying.
However, he turned down a request that Britain be allowed to investigate those detained after the Mumbai terror attacks.
The Prime Minister's comments came in his policy statement before the start of a debate on national security in the wake of the Mumbai terror attacks.
He said the British request came at a meeting with Prime Minister Gordon Brown on Sunday, but he told his British counterpart that if there is evidence against those arrested after the attacks, they would be prosecuted under Pakistani law.
Gilani thanked the opposition and treasury for being united on issues related to national security.