The governor on Tuesday told a televised press conference 18 suspects currently in custody had confessed to planning and preparing the 11 March bomb attack which saw two assailants storm the Association of the Grand Temple of Free and Accepted Masons of Turkey.
Police established the suspects "were about to carry out new suicide attacks after making plans and carrying out reconnaissance work," Guler said.
He added: "we know they received political and military training in camps in Afghanistan and Pakistan", but police had so far found no links between them and al-Qaida.
"It does not have links to currently-known organisations ... We are investigating whether it has links with al-Qaida," Guler added.
The London-based Arabic newspaper al-Quds al-Arabi said last week it had received a statement from an al-Qaida linked group, Jund al-Quds, or Soldiers of Jerusalem, claiming responsibility for the bombing.
"We know they received political and military training in camps in Afghanistan and Pakistan ... We are investigating whether it has links with al-Qaida"
The attack on the freemasons left two dead - including one of the bombers - and five injured.
It came nearly four months after four massive bombings in Istanbul which Turkish authorities blamed on Turks with links to al-Qaida.
Guler also said one of the suspects arrested had confessed to the 2003 killing of a Jewish dentist in Istanbul.