Brian McConnachie, QC, has also claimed the incident, which saw 13 supporters arrested during an unauthorised march to Celtic Park, could have been dealt with earlier in the week.
More than 200 officers, many on horses and with batons drawn, rushed to the scene of the demonstration in Gallowgate on Saturday afternoon.
Videos have been posted on social media sites and come after allegations by lawyers on the treatment of fans from all clubs under Offensive Behaviour At Football legislation.
The Green Brigade announced in midweek it intended to march to the game against Aberdeen over allegations of mistreatment since the laws were introduced a year ago.
But, before setting off, police moved in to halt them proceeding on the roads, known as "kettling".
Legal representatives, along with politicians, are now demanding answers from the police over the handling of the incident, which began outside the Chrystal Bell pub.
Mr McConnachie said: "From what I've seen, this is total overkill. I don't care which team you support.
"How can this be considered a proportionate response to what seemed to be a peaceful protest? We'll know pretty soon exactly what went on, given the amount of video footage.
"If the police believed there was going to be an issue they had days to resolve it. They had an opportunity to discuss it. It's pretty clear 200 officers with cameras and batons just seemed to be on hand for an unexpected incident."
Paul Mullen, from solicitors Livingstone Brown, added: "I very much doubt Strathclyde Police will have heard the last about the events of Saturday."
Glasgow SNP group leader Graeme Hendry has written to the head of Strathclyde Police Authority asking it to "launch an investigation into what happened".
A police spokeswoman said: "Any complaints will be fully investigated and we will examine all footage."