A video of the incident, which took place on Saturday afternoon (4 November) before Hull City faced Sheffield United, was posted on the Facebook and Twitter page of Hull City Protesters Group.
The group posted the video with the comment “we keep to our word smoke bombs gone off in a Sheffield pub”.
The group claimed the bomb, which filled the unnamed pub with orange mist, was set off in protest over the club’s current owner and chairman Assem Allam.
A spokesman for the group told the Hull Daily Mail that the smoke bomb was to cause an “inconvenience” in the hope the Allams - Assem's son Ehab is vice-chairman of Hull City FC - would get fined.
“The reason we put out the smoke bombs but never ourselves let them off is to try and be an inconvenience to any authority wherever we go hoping the Allams get fines and excessive paperwork,” they told the paper.
There was a largely negative reaction to the video, with some commenting that the move was just an “excuse for a bit of vandalism”.
Justin Kozikas posted the comment: “Instead of promoting your cause you have set back your cause. Hopefully you will think of something more appropriate to get media attention to the cause, dare say an apology to the pub owner will be a good start."
Darren Hatfield added: “So going to a local city on a Saturday afternoon in a pub where young parents and kids are having their lunch will want to be around that?
“I’m all for away atmosphere but, there’s a time and a place that just doesn't work.
“We're already getting a huge backlash from rival supporters who shared it to other forums. A lot of people don't think it was the best idea. Me included."
Replying to the comments, the protest group said: “Unfortunately we are going to upset some people, but we are an active protest group. What do you want us to do, wave flags and banners?”
However, talking to The Morning Advertiser, the group claimed it has "never taken responsibility" for the incident.
On dealing with similar situations, chief executive of the Association of Licensed Multiple Retailers, Kate Nicholls, said: “Managers should make sure that all team members are aware of all safety and security arrangements that are in place in the unlikely event of such an emergency occurring.
“Venues can consult their local authority for advice on security and safety planning, or members can contact the ALMR for help.
“The ALMR has also been working with the police to highlight crimes and attacks against premises and to push for closer, constructive working between the sector and police forces to ensure these incidents are not recorded against businesses.”