The tribunal arrived at its decision after hearing all stakeholders, including Marumalarchi Dravida Munnetra Kazhagam (MDMK) leader and Rajya Sabha MP Vaiko.
MP Vaiko is an LTTE sympathiser.
The tribunal, set up under the Unlawful Activities (Prevention) Act (UAPA), had held hearings in Delhi and Chennai after it was constituted on May 27.
India had banned the LTTE after the assassination of former prime minister Rajiv Gandhi in 1991. Since then, the ban imposed on the group has been extended every five years.
The terror organisation had suffered a military defeat in May 2009 in Sri Lanka.
The Ministry of Home Affairs had on May 14 extended the ban for five more years. The organisation was last banned in 2014 for five years.
While extending the ban on the LTTE, the Home Ministry in its May 14 notification had said that the group's continued violent and disruptive activities are prejudicial to the integrity and sovereignty of India, and it continues to adopt a strong anti-India posture and also continues to pose a grave threat to the security of Indian nationals.