Spain-based pair Alan Barratt, 62, and Susan Dalton, 66, who tricked 245 people into transferring their pension pots into fraudulent schemes, were last week put behind bars for their crimes.
Mr Opperman said their sentencing was "good news for pension savers and law-abiding citizens across the country".
Barratt and Dalton were part of a criminal enterprise which persuaded people to transfer their pension savings, worth around £55,000 on average and with a total value of £13.7 million, into the scam schemes.
Mr Opperman said: "These scammers deceived hundreds of savers, depriving them of security in retirement through their despicable actions. As minister for pensions, one of my key priorities is making sure people are protected from the devastating impact of pension cons and the callous crooks responsible for them."
He said pension trustees have already been given new powers to intervene if they "suspect someone's hard-earned pension savings will end up in a fraudster's grubby fingers".
The Government's Online Safety Bill, he added, will crack down on "dodgy adverts" which "lure people into these rip-offs".Pledging further action, he said: "[We are] not stopping there, knowing that as scammers' crooked techniques evolve, so must our defences. We're arming savers with the tools they need to spot these duplicitous fraudsters and stop them in their tracks - such as our MoneyHelper service and Action Fraud.
"This is a real joint effort, with collaboration across government, regulators, law enforcement, and industry. Let this court case be a message to those rip-off merchants who think they can ruin people's retirement: we won't rest until you end up behind bars."
Barratt was last week sentenced to five years and seven months. Dalton was sentenced to four years and eight months.
Delivering his judgement, Judge Gregory Perrins said the impact of their crimes has been "utterly devastating".
He said: "I heard about depression, anxiety, divorce and suicide attempts. Each account is a story of a life ruined and you should be ashamed of bringing such misery to so many innocent people."
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