Outrage against the privately owned television channel Imedi has sparked street demonstrations and condemnation by the politicians. Some viewers of the fake news report claimed they had to take medication to cope with the stress.
Giorgi Arveladze, head of Imedi, apologized for causing the panic, but said it had not been his intention to do so.
"The goal was not to scare society, the goal was to talk about those security threats which our country faces. Our goal was to openly lay out the plan prepared in Moscow with all its painful details," Arveladze said
The false broadcast included library footage of the real August 2008 Russian invasion, which Moscow claimed was intended to protect the breakaway Georgian states of Abkhazia and South Ossetia. Hundreds of people, including many Georgian civilians, lost their lives during that war.
The reporter said on Saturday's broadcast that Russian tanks were heading for the Georgian capital, and that president Mikheil Saakashvili had been killed and some opposition leaders had sided with the invading Russians.
There was a brief notice before the report aired saying it was a "simulation" of possible events, but the report itself carried no warning that it was untrue.
Imedi channel ran a ticker during a subsequent entertainment show stating the report "did not correspond with reality", but had no further explanation for why the report was broadcast at all.
Arveladze said, "It was a miscalculation to think that the society would have perceived the broadcast adequately."
He went on to say that no one at Imedi would face any disciplinary action over the incident. "I do not consider any changes in staff, neither my resignation," he said.
President Saakashvili said: "It was indeed a very unpleasant programme but the most unpleasant thing is that it is extremely close to what can happen and to what Georgia's enemy has conceived."