Best, who plays mechanic Dexter Harman in the BBC One soap, allegedly left 63-year-old Peter Callow with a bleeding black eye and £600-worth of damage.
It came just months after he was named Best Newcomer at the National Television Awards.
Cautioned by police for criminal damage and common assault, the 26-year-old star was also suspended from his role in EastEnders for three months following the attack in March.
Best was leaving the Television and Radio Industries Club Awards at London's Grosvenor Hotel when he hailed Mr Callow's cab and asked for a lift to Enfield in north London.
But he soon realised he had no money for the trip - which lasted 45 minutes and cost £61 - and began to phone friends, according to the Sun on Sunday's Dan Sales.
Mr Callow told the paper: 'I told him if he had a card he could put it into the machine I had in the cab but he wasn't having any of it.
'He then said "No, no, no" and with that he started kicking the car door. I got round to stop him doing it and he managed to open the door and thumped me.'
Left with an alleged £600-worth of damage, Mr Callow contacted police, who attended Best's flat.
A Metropolitan Police spokesman said: 'Officers from Enfield CID investigated an allegation of assault on March 11 in Enfield.'
He added that a man 'from the EN3 area attended a north London police station on 9th April and received a conditional caution for common assault and criminal damage'.
In May, it emerged the star had been suspended from his role in the soap for three months.
A BBC spokesperson said: 'Khali Best has been suspended from EastEnders for three months. We will not comment any further on this matter.'
A poll has been set up whether actor & thug Khali Best should keep his job after attacking a Taxi driver