Businesses should not legally be allowed to refuse cash, MPs have been told.
People on lower incomes, the elderly and disabled people are among 10 million who would become "financially excluded" in a cashless society, a debate heard.
It comes after nearly 60,000 people signed petitions to Parliament calling for it to be illegal for retailers and services to only accept cards.
SNP MP Martyn Day said: "For some of our constituents not being able to use cash is a profound barrier in everyday life.
"Cash can be a vital means of budgeting."
He cited figures from The Royal Society for the Encouragement of Arts, Manufactures and Commerce (RSA), which last year found 15 million people rely on cash for budgeting.
Mr Day told a Westminster Hall debate: "The ability to use cash should be protected." And he added: "The march towards going cashless risks the exclusion of a great many people."
The government has said it has no plan to make accepting cash a legal requirement - which Mr Day said is "not good enough".
Labour's Tulip Siddiq told the debate that 3.8 million people in financial difficulty are reliant on using cash for budgeting, stating: "As the cost of living crisis deepens, the poorest in society are using cash to manage their budget on a week by week basis - and sometimes day-to-day."
She called on the government to carry out research on cash acceptance.
Tory Duncan Baker said: "Despite the advancement of technology it's absolutely clear to me that the acceptance of cash should remain a viable option for the foreseeable future.
"The public aren't in a position to close that door."
One petition put before MPs said: "Not everyone wants a digital trail and others simply cannot pay by card."
Another, signed by 25,000 people, says: "As many businesses and taxpayer-funded public services are increasingly insisting upon cashless payments, it is important that we safeguard against the potential dangers of this practice. It creates an enforced dependency on banks, even though they cannot always be trusted to act ethically, and is a threat to privacy as people cannot make anonymous payments."
In response to the petitions, the government said: "The government does not plan to mandate cash acceptance.
"While the government recognises the ability to transact in cash remains important to millions of people across the UK, particularly those in vulnerable groups, it remains the choice of individual businesses as to whether to accept or decline any form of payment, including cash or card.
"This may be based on factors such as customer preference and cost."
Treasury minister Andrew Griffith said there is "no plan, no drive, no conspiracy" to eliminate cash.
He added: "The Government continues to support the ability to use cash alongside digital payments."
