Mr Kreitman, who lives in Tel Aviv, told Israeli TV that he was sitting in a nearby bar having a drink when he heard gunfire.
He was in a position to help as he was carrying a handgun due to his status as an IDF reservist soldier.
Mr Kreitman attended the Nova event on October 7 – which was attacked by Hamas terrorists – due to his involvement with Israel’s festival of vibrant culture.
He has been the CEO of Midburn, Burning Man Festival’s regional event in Israel, since 2023.
The attack happened in the neighbourhood of Jaffa, a mixed Arab-Jewish neighbourhood in southern Tel Aviv, on Tuesday.
It began just moments before Iran fired a barrage of 180 ballistic missiles at Israel, forcing residents to pile into bomb shelters across the country.
The gunmen have been identified as Mehmed Khalaf Saher Rajab and Hassan Mohammed Hassan Tamimi, both from the West Bank city of Hebron.
Police said the pair were in Israel illegally and were killed at the scene by light rail security guards and municipal emergency units, with the help of police and civilians.
Initial investigations revealed that one of the attackers was armed with an M-16 rifle while the other carried a knife.