The Chancellor was panned after a statement to the Commons on Tuesday where she rehearsed previous cost of living commitments without bringing forward new policies.
Bills are expected to soar when energy prices change at the end of June, having been cut and frozen for three months from the start of April.
Energy bills are set to increase by £332 a year in July, taking average annual bills to £1,973, according to analysis from Cornwall Insight.
This would mean that energy bills would be up £405 since Labour came to power, despite their previous pledge to cut prices.
Reeves told the Commons that the economic impact of the war in Iran would be “significant” but said that contingency planning was taking place for “every eventuality”.
Though she did not announce any new measures to help tackle the cost of living, the Chancellor told MPs that Labour had previously taken measures to help ease financial pressures, including cutting the energy cap and freezing prices for the next three months.
But she repeatedly hit out at Liz Truss, who presided over the last energy shock caused by the invasion of Ukraine, which capped bills for two years.
Reeves said that “unfunded, untargeted” approach spooked the markets, pushing up borrowing, interest rates, inflation and mortgage costs, adding: “That left us with high levels of national debt, a cheque written then for a bill that is still being paid today.”
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She added: “Contingency planning is taking place for every eventuality so that we can keep costs down for everyone and provide support for those who need it most, acting within our iron-clad fiscal rules to keep inflation and interest rates as low as possible.
“This is not a war that we started, nor is it a war that we joined… but it is a war that will have an impact on our country.
“The challenges may be significant but I promise to do what is right and fair, being responsive in a changing world and responsible in the national interest.”
Dave Doogan, the SNP economy spokesperson, said: “The Labour Party‘s failure to deliver any meaningful support for the overwhelming majority of families is a total betrayal, which will leave millions of Scottish households in the lurch as bills soar on Keir Starmer‘s watch.
“Today’s statement from the Chancellor was absolutely pathetic. It is a disgrace that the Labour Party is refusing to lift a finger to support the majority of working families and, it is, yet another broken promise from a Chancellor who told voters she would reduce everyone’s energy bills by £300 only to preside over sky-high bills that could soon be £700 higher than promised.
“Scotland is an energy-rich country – and it is a scandal that, under the Labour Party, Scottish families are being forced to pay among the highest energy bills in Europe while the Treasury takes more than £350billion of Scotland’s energy wealth for Westminster.”
Zack Polanski, the leader of the Green Party of England and Wales, slammed Reeves’s “unbelievably weak response”. He added: “Reeves’s lukewarm words show that she and her government simply do not understand the scale of the cost of living crisis about to hit this country.
“We need a guarantee that energy bills will not rise past June, funded by a strengthened windfall tax and higher taxes on extreme wealth. And the government should follow the example set by Spain in taking immediate action to reduce the burden on households by freezing rents.”
Reeves confirmed to the House that the UK Government was “encouraging investment in tiebacks to make the most of our existing production facilities”, which allows an existing production facility to be linked to a new field.
Elsewhere, she told MPs that the Government hoped to reduce food prices by signing a trade deal with the EU this year and that the competition watchdog would get new powers to tackle price gouging.
