Gardai were warned that a Kinahan cartel hit team was travelling to the north inner city to carry out a murder this week sparking a major alert.
The tip-off led gardai to advise unarmed officers not to stop any suspect vehicles without the assistance of armed back-up.
Unarmed gardai were also told not to attend any firearms incidents without having armed officers with them.
The alert was issued to gardai working in the capital's north inner city at around 10pm on Thursday.
The warning about the hit team came following investigations from the Garda Drugs and Organised Crime Bureau (DOCB).
Sources say that detectives may have received the tip-off from a planted listening device, a bugged phone call or a garda informer.
Gardai who man permanent checkpoints in the vicinity of the Hutch clan in the north inner city were also warned about the hit team.
"Thursday night's alert shows that the feud has certainly not ended and tensions remain very high," a senior source said.
"Its purpose was to make sure that gardai exercised caution and were very careful. There is a high level of concern that an unarmed garda could get caught in the crossfire between these gangs. These kind of alerts have popped up before and it is important that gardai are as safe as possible while carrying out their duties.
"There has not been a murder in this feud for over three months now but that does not mean it is over."
There were no firearms incidents in the city on the night and detectives did not intercept a car containing gang members.
The development came as sources said that it is believed that members of the Hutch gang once again have access to a large haul of heavy-duty firearms. Tensions could also increase if, as expected, a number of senior cartel figures are back in Ireland next week.
There have been no major incidents in the capital's deadly feud since the murder of Noel 'Duck Egg' Kirwan, who was shot dead in Ronanstown on December 22, 2016.
Since then, gardai have made a number of significant firearms and drugs seizures from the cartel.
A total of 11 men have been shot dead in the bloody feud since it started with the murder of Gary Hutch in Spain in September 2015.
It exploded when his associates carried out the Regency Hotel revenge attack in February of last year and murdered cartel figure David Byrne (33).
In late December, gardai said that they had foiled at least 15 feud murders in 2016. A figure for this year to date has not been disclosed.
Speaking to the Herald in December, Detective Superintendent Howard, of the DOCB, said the number of feud murders would have been significantly higher had it not been for the last-minute interventions of gardai.
"There were at least 15 occasions when we had to react quite quickly because there was an imminent threat to somebody's life," he said.
"We're talking minutes to a couple of hours away from the attack being carried out. It's really all hands to the pump at that stage."
Earlier this week, Byrne's close pal Richard O'Reilly (32) was jailed for six years after being found in possession of a handgun, ammunition and a can of petrol.
O'Reilly had been the subject of a surveillance operation by detectives in the days before he was arrested last June.
When the car O'Reilly was in was stopped at Walkinstown, it is believed that he was on the way to kill at least one member of the rival Hutch mob.