Abbasi had earlier said that there was 'no evidence' against him and was 'absolutely innocent'.
US State Department spokeswoman Heather Nauert said on Friday, "We regard him as a terrorist, a part of a foreign terrorist organisation. He was the mastermind, we believe, of the 2008 Mumbai attacks which killed many people, including Americans as well."
"We condemn the statement made by Prime Minister Abbasi. We have made our points and our concerns to the Pakistani Government very clear. We believe that this individual should be prosecuted to the fullest extent of the law", the statement added.
The State Department spokesperson stressed that Saeed's name was on the UN's list of designated terrorists, adding: "He is listed by the UN Security Council 1267, the Al Qaeda Sanctions Committee for targeted sanctions due to his affiliation with Lashkar-e-Taiba (LeT), which is a designated foreign terrorist organisation".
The Ministry of External Affairs (MEA) Spokesperson Raveesh Kumar on Friday said, "If somebody is a designated global terrorist, it's done based on a lot of evidence available in public domain. You can close your eyes, pretend nothing happened but they (Pakistan) have to realise what's in front of them and take action against such people, who are freely operating from their soil".
Saeed was released from house arrest after a Pakistani court cited lack of evidence against him in the 26/11 Mumbai attack case.