The Government now needs to rapidly deliver supports for businesses impacted by the new restrictions, Chambers Ireland has said.
Under the plan, non-essential retail services will close.
Chambers Ireland has said the shutdown time must be used to ensure infrastructure is in place to help local economies to reopen.
"It is desperately sad and frustrating that we find ourselves shuttering our country again in the face of this rising wave of Covid-19 cases," said Ian Talbot, chief executive of Chambers Ireland.
"Today's news of further restrictions will be devastating for many people."
"However, we must look forward. As we have been through the experience of restrictions before, we now know better what needs to be done."
It also said the Covid Restrictions Support Scheme must be made available right away.
"Wage supports for employees and the self-employed will need to be increased if businesses are to be able to continue through the restriction period.
Extensions to CRO and Revenue filing deadlines should also be considered," Mr Talbot said.
It said a credible exit strategy needs is now needed so we avoid successive waves of opening and closing the economy.
The Construction Industry Federation said it welcomed the Government's decision to allow construction to remain operating under the strictest safety procedures.
It said construction companies and employees will now redouble efforts to deliver housing and critical infrastructure for the economy in the safest possible manner.
"Remaining open during level five is testament to the incredible efforts over the past five months in keeping the incidence of Covid-19 to a minimum on construction sites," it said.
Retailer Excellence Ireland said it is deeply disappointed by the decision to close all non-essential retail.
It said retailers had invested heavily in making premises safe, had been compliant with guidelines and pointed out that no other European country has locked down retail in this way.
"Retailers have been contacting us throughout the day extremely concerned and upset at closing their business for 6 weeks at the most important trading period of the year," said Duncan Graham, CEO of the organisations.
"Non-essential' retailers generate over 70% of annual turnover over this quarter and these further restrictions will inevitably push many more businesses into insolvency."
REI predicted that 60,000 retail employees will lose their jobs as a result of the new measures joining the 30,000 retail workers who have already been laid off this year.
It also said the closure would lead to unprecedented pent up demand when retailers reopen in December, resulting in a "frenzied shopping experience" in the final weeks before Christmas.
DublinTown, the organisation that represents 2,500 businesses in Dublin city centre, said they expect a significant level of business closures as a result of the restrictions.
Earlier the founder of the retail strategy website PTO.ie said Level 5 restrictions will be devastating for anyone in the retail and hospitality sectors.
However, Miriam Simon said it is more important that action is taken now so everyone can celebrate Christmas.
Speaking on RTÉ's Six One News, Ms Simon said that while what is being considered may seem unfair, it's important that retailers understand they are not being told to stop trading completely.
There are many ways to keep the lights on and keep trading, she said.
Ms Simon also added that it's important for retailers to seek support and help wherever they can, and to communicate with their customers to let them know they are still there.
She urged shoppers to spend their money at Irish stores and said livelihoods depend on it.
The Irish Hairdressers Federation (IHF) has expressed regret and disappointment at the impending Government restrictions on hairdressers and salons.
The IHF said its members believe they should remain open as their salons have carefully followed all necessary measures to combat COVID-19.
"From day one when we reopened, we have followed all guidelines and looked after our customers in a safe environment," said Lisa Eccles, Vice-President of the organisation.
"We are doing our very best to support jobs and remain open."