Mr Byrne was shot dead in the Regency Hotel during a boxing weigh-in in the north of the city in February.
This is the second search to be carried out in a week.
RTÉ has reported that searches are being carried out on ten houses and flats in Dublin's south inner city.
The operation began at around 06:30 local time on Friday morning.
It is understood that over 80 armed gardaí are involved in the investigation, as well as the Emergency Response Unit, the Drugs and Organised Crime unit and the Criminal Asset Bureau.
On Wednesday, Irish authorities seized over 1m euros (£770,000) worth of luxury cars, cash and other valuables.

Jacqui Thompson was arrested in 2011 for filming a Carmarthenshire council meeting and sued Mark James for libel.
He counter-sued for posts made on her blog and received £25,000 in damages.
The Crown Prosecution Service (CPS) said Mrs Thompson had been charged with an harassment offence but a decision was taken to discontinue her case.
Mrs Thompson, of Llanwrda, said she was "relieved" at the news and had been worried about her impending court case, which was due to take place on Thursday.
A CPS spokesman said: "Following a review, prosecutors were no longer satisfied there was a realistic prospect of conviction due to insufficient evidence and therefore made the decision to discontinue the case."
Mrs Thompson became embroiled in the legal row after she was arrested in June 2011 for refusing to stop filming a council meeting for her blog, in which she was critical of the authority.
She sued Mr James the following November and he successfully counter-sued in a private lawsuit.
In 2016, the High Court found Mrs Thompson had run a campaign of "harassment, defamation and intimidation" against Mr James.
She was told to pay back £250 a month to him over the next 10 years to cover the damages.
Carmarthenshire council covered Mr James' legal costs, a decision the Wales Audit Office later found to be unlawful.
But the authority is pursuing Mrs Thompson for £190,393 in legal costs.
The council would not comment on the latest development in the case, which it said was a private matter for Mr James.
Mr James has been asked to comment.

Jade Ali, 28, said she had been "left in the dark" about the search for partner Christopher Huxtable, 34.
He is one of three men believed to be trapped under the debris of the decommissioned power station.
The Health and Safety Executive said its priority was to recover bodies from the rubble.
Updates on this story and more from Oxfordshire
But Ms Ali, from Swansea, said she felt rescuers had given up their search too early.
"There's still a chance Christopher could still be alive," she said.
One person died and five were injured after half of the 10-storey building collapsed on 23 February.
Police said it was "highly unlikely" that the missing were still alive and that recovering bodies would take "many, many weeks".
John Howley, the uncle of Rotherham-based demolition worker Ken Cresswell, who is also believed to be trapped in the rubble, said there had been a "diabolical" delay in getting to the missing men.
He said: "It is just the uncertainty - you are hoping that they are still alive in there, but you have got to be realistic and think that it has been going on too long now."
The Sun has reported that the third victim is John Shaw, also believed to be from Rotherham, South Yorkshire.
Site supervisor Mathew Mowat said he was seconds from being buried by the collapse.
He said: "I feel guilty in not being under there with the guys and for coming home because they are still there left under that steel - it is ridiculous they are not out."
A Health and Safety Executive spokesman said: "The priority of the multi-agency response remains the recovery of the bodies to their families.
"Given the risks, scale and complexity of the incident and that the building collapsed without warning, emergency services have had to strike a very difficult balance between helping those trapped and injured, recovering the bodies and the need to avoid further harm on the site."
Thames Valley Police said it met with the families of the victims on Monday and the structure was still "unsafe". They are seeking "specialist advice" on how to progress.
A spokesperson added: "Our priority remains the recovery of their loved ones so they can be returned to their families and to understand what caused this incident."
Irish police have begun another series of raids on properties linked to members of a criminal gang connected to shooting victim David Byrne in Dublin.
[NEXT_CONCEPT]
A blogger who launched a "campaign of harassment" against a council chief executive has had the criminal case against her dropped.
[NEXT_CONCEPT]
Two of the three families of missing workers feared trapped at the collapsed Didcot A Power Station have criticised emergency services' rescue attempts.