Billy McAllister, 48, told John Park to "f*** off" and said "You're f****** rumbled" when they both went to a meeting where Tommy Sheridan was speaking, in Ardoch Street, Possilpark last year.
The SNP deputy leader was so aggressive when he shouted to Mr Park - a member of the Solidarity party - that he was "almost spitting" and had to be forcefully held back and was eventually dragged away.
Mr Park - who has metal plates in his leg and a crushed vertebrae - then went to the reception area of the Millenium centre where the meeting was held, and the police were called.
At Glasgow Sheriff Court McAllister pled guilty to acting in a threatening or abusive manner and shouting, swearing and gesticulating aggressively towards Mr Park on May 29, last year.
A not guilty plea to a charge of assault by pressing a key into Mr Park's face was accepted by the Crown.
McAllister was fined £200 by sheriff Lindsay Wood.
Speaking after the case Mr Park alleged he was threatened by McAllister and felt he was being goaded by him outside the meeting.