Greek police have broken up an attempt by Golden Dawn to hand out food to only Greeks, in defiance of a municipal ban, with Giorgos Kaminis, the city's mayor, saying one of the ultra-nationalist party's politicians tried to punch him and draw a gun.
The party, whose members have been repeatedly linked with violent attacks on Greece's large immigrant population, had said it would give food to needy Greek citizens in Syntagma Square ahead of Sunday's Orthodox Easter.
Kaminis had pledged to ban the event which he called "racist and xenophobic".
The punch by Giorgos Germenis, which was said to have taken place at a municipal charity distribution centre, missed Kaminis, landing instead on a 12-year-old girl, Greek media reported.
Security guards then restrained Germenis, with television footage showing them marching him out of the building.
"The only thing these people know is the language of violence," Kaminis said on state television after the incident during his visit to the centre.
Party members, the Golden Dawn logo emblazoned across the back of their black T-shirts, arrived at the square more than two hours earlier than announced and began handing out bags of food after checking recipients' identity cards.
Scuffles broke out between the party members and riot police as authorities prevented the party's truck from unloading its cargo of meat and other goods.
Police used pepper spray to repel other party members holding Greek flags on thick wooden sticks, and the truck was eventually forced to move on.
The party resumed its distribution from party offices in an inner Athens neighbourhood.
Kaminis later visited the municipal food distribution centre in the same area when he was confronted by Germenis.
"This man sneaked in, we didn't notice him ... and he tried to hit me," Kaminis told Vima FM radio.
"At the last minute my personal guards stopped him. This man is armed. He attempted to pull [the gun] out."
Greek media said the girl who was hit by the punch was not badly hurt, and suffered a bruised forehead.
Golden Dawn, a once-marginal group fond of Nazi literature and symbols but which rejects the neo-Nazi label, is now Greece's third-most popular party and won 18 of parliament's 300 seats in elections last year.
With the country mired in the sixth year of a deep recession and poverty levels spiralling, it has staged Greeks-only food distributions elsewhere in the past that have proved popular.