Video report by ITV News Sports Reporter Chris Skudder
Police tried to hold back supporters as they crowded manager Steven Gerrard's car as he entered the ground.
Police said no arrests have been made.
Under coronavirus rules, public gatherings are banned and a maximum of two people from two households are allowed to meet outdoors.
Football games are continuing to take place behind closed doors with no fans permitted inside stadiums.
After beating St Mirren 3-0, Rangers only need Celtic to lose against Dundee United on Sunday to win the league title.
Chief Superintendent Mark Sutherland said: “About 10am today… a large number of supporters gathered outside Ibrox Stadium and a number of pyrotechnic devices were set off.
“I would remind supporters that in line with current Scottish government coronavirus guidelines, all gatherings are currently prohibited and we would urge members of the public to comply with these restrictions.
“Our priority is public safety and an appropriate policing plan was in place and officers engaged with those present to explain and encourage compliance with restrictions.”
Steven Gerrard said safety was "paramount", but also empathised with the fans.
"We are still experiencing and are involved in a pandemic. It’s important fans try to stay humble and safe," he said.
“That’s the priority – people’s safety. I totally understand that.
“But at the same time, if you’ve got anything inside you or any part of your heart can understand what the fans have been through, you can totally understand what’s gone on outside this stadium.
“It’s my job to try and control that. Safety is paramount at the moment but it’s tough because it has been an emotional three years for me. The fans have been here for much longer than that and have been through a lot in 10 years. So you can certainly understand it.”
A spokesperson for the Scottish government said: “We are extremely disappointed supporters have gathered at Ibrox today.
“At this crucial stage of suppressing the virus, the actions of this minority of individuals jeopardises the safety of other supporters, the police on duty and the wider community.
“We will continue to engage with Police Scotland and the club.”
First Minister Nicola Sturgeon has previously criticised fans for gathering in large numbers.
After Celtic fans took part in a protest outside the club’s stadium in November, she said: “We have advice against gatherings and every day I stand up here and say avoid crowded places.
“We have a limit on people coming together outside… so it stands to reason any group of people that are gathering together in a crowd are putting themselves and others at risk.
“Whether it’s football fans, rugby fans, any other kind of sport fans or just people in general, please don’t do it because right now, in the middle of this pandemic, it is a risky thing to do that puts you and other people at risk.”
The Blues Brothers Rangers and Linfield FC fan group posted videos of the gathering on Twitter.
A member of the group told the PA news agency: “It’s scenes of joy. Ten years almost of pain and watching our rivals win the lot has been hard to take. It’s scenes of relief to stop the 10 in a row.
“We’d expect celebrations to be bigger when Rangers officially do win the title, whether that’s tomorrow or two weeks’ time against Celtic.”
Twitter user @rangersnt, from Glasgow, was also there and said: “Outstanding scenes, it’s been such a long time since we have won the league, we don’t want to miss out on one of the biggest moments in our history, to celebrate our teams achievements and (Rangers manager) Steven Gerrard getting us back to where we belong.”
Asked about the coronavirus restrictions, he said: “It’s up to everyone themselves and how they feel on the ongoing situation.”
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