Some consumers had not given consent to be called
The Office of Fair Trading has warned 10 firms to stop making unsolicited and misleading calls to advertise services.
The six debt management and four cold-calling firms were told they could face formal action if they failed to stop.
It came after the trading watchdog and the Information Commissioner's Office received a large number of complaints about the firms, which cannot be named.
The OFT said it was "completely unacceptable" for companies to take advantage of people with debt problems.
Some firms may also have broken the law with the calls, the OFT said.
"Taking advantage of people who are suffering distress through debt problems is completely unacceptable and this practice of illegal or misleading cold-calling for debt management services must cease immediately," said Nigel Cates, deputy director of consumer credit at the OFT.
"The current economic climate means that it is vitally important vulnerable consumers are protected. We will not hesitate to take action against any business that uses misleading calls to advertise debt management services."
Mick Gorrill, assistant information commissioner at the ICO, said: "The ICO has received a large number of complaints about automated marketing calls promoting debt management schemes. We have worked closely with the OFT on this issue and welcome the action taken."
Some callers were told they were some of the "few chosen individuals" who had been contacted as part of a government scheme to help wipe out consumer debt.
Others were transferred to a debt management business on the pretext of being passed on to a not-for-profit debt adviser.
They often failed to be honest about the reason for the call and the caller's identity.
One of the bodies which provided evidence to the OFT about the practices was Citizens Advice, which offers free information and advice to people with financial worries.
Teresa Perchard, director of public policy for the service, said the callers are "not upfront about who they are".
"It's very intrusive and disconcerting if someone rings you up and says this is a confirmation call about your debt. People worry a lot about what's on their credit reference files these days, for example", she told the BBC.
"But failing to tell people who you are and why you're ringing is misleading people."
The firms that could have broken the law had done so by pestering people who had not given their consent to be called or who had registered with the Telephone Preference Service, which allows people to opt out of receiving sales and telemarketing calls.