Boris Johnson has been accused by a former Conservative leader of "giving in" to the government's scientific advisers and "marching England back into another lockdown".
Iain Duncan Smith said the announcement of a second national shutdown is a "body blow to the British people".
In a news conference on Saturday, the prime minister said there will be a month-long lockdown in England that will begin on Thursday.
Before that, MPs will vote on the latest restrictions on Wednesday.
Labour leader Sir Keir Starmer has said his party will vote in favour of the lockdown, meaning the government won't be defeated in the Commons.
But a number of Conservative MPs have voiced their unhappiness and spoken out about the country going back into lockdown again.
Mr Duncan Smith, who was Conservative leader from 2001 to 2003, said the lockdown comes "just as the economy was picking up, even giving cause for optimism".
He added: "The way that the government's Scientific Advisory Group for Emergencies (SAGE) has pressurised the government into taking this decision has been unprecedented.
"Normally, advisers advise & ministers decide. Yet that system has broken down, with SAGE believing its advice to be more like commandments written on stone and its members publicly lecturing the government over the airways when it disagrees.
"This is despite the fact that many of its recommendations have been hotly disputed by other reputable scientists."
Sir Desmond Swayne, Tory MP for New Forest West in Hampshire, told Sky News "it will take a huge amount of persuasion for me to vote for this disastrous course of action".
"I'm not persuaded that the cost of the intervention we're about to make, with disastrous consequences, is worth the candle," he said.
"I think we've chosen a course that is worse than deaths from the virus."
Sir Robert Syms has said he will vote against a second lockdown.
"Rather underwhelmed by [the] press conference, expected better case for lockdown and more detail," the MP for Poole in Dorset wrote on Twitter after Mr Johnson's news conference.
Wokingham MP John Redwood has also voiced scepticism, tweeting: "If the case for lock down is worry about NHS capacity, why is the forecast for hospital admissions a huge range including fewer cases than the NHS managed earlier this year?"
He added in another message: "What is the exit strategy from national lock down?"
David Davis, who was Brexit secretary under Theresa May, has suggested that a number of his Conservative colleagues could vote against the shutdown.
Speaking to Times Radio before the PM's announcement, he said MPs have "got to see the data" behind the move in order to be convinced.
Meanwhile, the government has been accused of displaying "contempt" for leaders in the North after announcing a national lockdown and extending the furlough scheme.
Politicians there had been calling for employees of businesses forced to close under Tier 3 restrictions to be paid 80% of their wages, but workers were instead offered 67% through the Job Support Scheme.
Liverpool mayor Joe Anderson told BBC Breakfast: "It's interesting as well, isn't it, that of course yesterday evening they announced that the furlough scheme would return at 80%, something that Andy Burnham, Steve Rotheram, leaders of the North, myself included, have been calling for.
"That's the point about contempt... that they dismissed the North's call for the furlough scheme to be introduced in Tier 3 but now have all of a sudden found the 80% furlough scheme for a Tier 4 or national lockdown."
Replying to a tweet from Chancellor Rishi Sunak, Greater Manchester mayor Andy Burnham said: "But when we asked you to do that for the lowest-paid people in the North, you refused. People here will remember that."
And Liverpool City Region Mayor Steve Rotheram tweeted: "Now we know for sure that the government thinks workers in the North were worth 13% less than those in the South."