Sir Jeffrey Donaldson said Covid-19 is "no joking matter" when asked about Sammy Wilson's controversial "ding dong" tweet about the Omicron variant.
The DUP leader addressed the controversy during a visit to the Shankill Road on Thursday afternoon.
However, he would not be drawn on if the East Antrim MP should have posted the comment.
Asked about the UUP's comments on Mr Wilson's tweet, the Lagan Valley MP said: "Covid is no joking matter. People have died from Covid, that is clear.
"And I think it is incumbent on all public representatives to support the public health messaging, to ensure that we all take the steps that are necessary to protect ourselves and each other, that we get vaccinated, and we get our booster jabs.
"All of this is essential to ease pressure on the health service this winter and ensure that we get through this winter without lockdowns, without people being out of work, with our schools remaining open.
"This is crucially important, and I am clear that as leader of the DUP we support the public health guidance, we want people to follow that public health guidance, we want people to get their injections, their vaccinations so we can work through this and see Northern Ireland through the other side this winter in a strong place."
Asked if Mr Wilson should not have posted the tweet, Sir Jeffrey replied: "I am very clear as leader of the DUP about positions of my party and I will be speaking to all of my colleagues to ensure that we follow, and support and promote the public health guidance when it comes to Covid."
Earlier the MP said party colleagues should “support public health messaging”.
He made the call after three of his MPs voted against imposing new Covid-19 measures in England.
Donaldson told the BBC’s Stephen Nolan Radio Ulster show: “As we wait for more information about the Omicron variant, we must follow the scientific and medical guidance. Everyone should do likewise.
“I want all my colleagues to support public health messaging. Unless exempt, everyone should get their jab and wear their face covering and help protect each other.”
On Tuesday, Mr Wilson tweeted: “Ding dong merrily on high will be replaced this Christmas by ping-dong miserably we sigh.
“I will vote against new restrictions in Parliament today. They are not proportionate to deal with the spread of the mild omicron variant.”
Full scientific studies regarding the severity of the Omicron variant of Covid-19 have not yet been conducted, with UK Health Secretary Sajid Javid confirming more is expected to be known in around three weeks.
Later that day alongside DUP members Paul Girvan and Ian Paisley, the East Antrim MP voted against new coronavirus restrictions in Westminster for England only, which included the requirement to wear face coverings indoors.
The UUP branded the votes of the DUP MPs in Westminster as “double-speak” and called on Sir Jeffrey to “take control of his party”, criticising Mr Wilson’s social media post as “distasteful”.
Ding dong merrily on high will be replaced this Christmas by ping-dong miserably we sigh.— Sammy Wilson MP (@eastantrimmp) November 30, 2021
I will vote against new restrictions in Parliament today.
They are not proportionate to deal with the spread of the mild omicron variant.
The requirement to wear face coverings in certain indoor settings remains a legal requirement in Northern Ireland, with First Minister Paul Givan previously explaining the measure would be retained as part of Stormont’s winter contingency plan for the virus.
Virologist Dr Ultan Power told the BBC that the majority of people who experience any of the Covid-19 variants “have relatively mild disease” and symptoms.
However, he said when just 10% of people needed hospital treatment that quickly put an overwhelming strain on the health system.
“That’s what then triggers the decisions about whether or not we need to go into lockdown,” the Queen’s University professor added.
“We’re much more fortunate whereby the vaccines have been rolled out, We know that the vaccines, especially the booster, have a major impact on the severity of the disease and therefore blocking people going to hospital, but more importantly... of the patients that you’ve seen, how many are vaccinated?
“There’s loads of questions that need to be addressed before we make definitive action.”
He stressed there was no need to panic but said government officials should take the new variant seriously so as not to allow a “situation to develop like we did with the Delta variant last year”.
“It would be really negligent to allow a similar situation to arise with this variant” said Dr Power.
He said there were various mutations within Omicron that may have consequences on the efficacy of the coronavirus vaccines.
The head of Moderna, creator of one of the most globally distributed Covid vaccinations, has also expressed concerns about this, although it has not been scientifically confirmed yet.
The company president, Stephen Hoge said Moderna could have a Covid-19 booster shot targeting the Omicron variant specifically ready for US authorisation as soon as March.
The Belfast Telegraph has approached the DUP for comment.