Hariri, a former prime minister of Lebanon, was assassinated in a massive suicide bombing in downtown Beirut in February 2005. A U.N.-backed Special Tribunal for Lebanon is investigating the circumstances surround the assassination.
Many believe Syrian officials and members of Hezbollah played a role in the plot. A 2009 report in the German news magazine Der Spiegel said cellphone records linked Hezbollah operatives to the planning of the operation.
Nasrallah in an interview with Hezbollah's news station al-Manar confirmed members of the STL had interviewed Hezbollah officials during their investigation.
The Hezbollah leader said as many as 12 members of his Shiite resistance movement were summoned "as witnesses, not suspects" for questioning in recent weeks.
He denied allegations that Hezbollah played a role in the Hariri assassination, saying the accusations were part of a broader effort to undermine his movement.
"We have been a target for years," he said. "The objective is to distort Hezbollah's image and pressure and intimidate the party."
Saad Hariri, the Lebanese prime minister and son of Rafik Hariri, said during a visit to Bulgaria this week that "we will accept any decision by the STL and deal with it as it is."
There is no time line for the judicial work of the STL.