Labour leader Alan Kelly says a move to only allow vaccinated people access indoor dining is 'absolutely bananas' and discriminatory.
It comes as the return of indoor activities is being delayed by at least two weeks.
Taoiseach Micheál Martin earlier said the country is in a race between the vaccine rollout and the Delta variant.
A number of indoor activities had been due to resume from next week, but those plans have been postponed.
Indoor dining is expected to open to fully vaccinated people or those who have recovered from COVID sometime after July 19th, with a system for managing it being worked out over the coming weeks.
Mr Kelly told The Hard Shoulder it will see a situation where hospitality will be offered to vaccinated people by unvaccinated workers.
"I believe, as I said in the Dáil, what they're doing now is discriminatory.
"And what they should have done is, effectively, said 'Look we know we've an issue here, we know that we have to deal with it'.
"And the way to deal with it is have all the pharmacies across Ireland administer the Janssen vaccine immediately - which is here, present, we have them and we'll have more.
"And also [for] mass vaccination centres to go to AstraZeneca.
"In two weeks' time, we were going to be at 70% one dose and 50% two doses.
"In two weeks' time, if we did what I just said, we'd be up to 55/56 or 75/76.
"We'd have two more weeks of data and then we'd be able to make an assessment - that's what I think they should have done".
'They'll have to reverse on this'
Mr Kelly says they were right not to re-open hospitality on July 5th, but what is proposed is unworkable.
"I wouldn't have an issue if they actually came and said 'Look, we need a few more weeks because of what's arising here'.
"That's what I think they should have done - what they're proposing now is insane, it is absolutely bananas.
"And I can tell you, having spoken to a number of people in the Government at the Cabinet table, they believe that this will probably have to be jettisoned, they'll have to reverse on this.
"It's unenforceable and it can't work.
"You're going to have a situation here where... you're going to have basically hospitality for the vaccinated provided by the unvaccinated."
Easing restrictions: Here's what's happening on July 5th
He says the decisions being made do not seem to be based in law, and parameters need to be set for NPHET.
"Whatever advice you give us has to be based in Irish and European law - we have to operate within law - and the second one is whatever you advise we're not going to discriminate.
"That did not happen, those parameters are not set out.
"The ridiculous situation now where the public advice is that people who aren't vaccinated shouldn't travel - but we all know that European law trumps it and they can travel".
The announcements followed a stark warning from the National Public Health Emergency Team (NPHET) about the risks posed by the Delta variant.
The health body warned the Government that in a worst-case scenario, Ireland could see more than 2,000 deaths COVID-19 related deaths by September.
However a more optimistic projection it put the number of deaths at 165.