Appearing at the liaison committee hearing, Sir Keir said he “welcomed the talks” between the US and Iran and added that the UK had been aware they were happening.
“The immediate priority has to be a swift resolution of the conflict and delivering a negotiated agreement which puts tough conditions on Iran, particularly in relation to nuclear weapons,” he added.
However, he warned there was “no certainty” talks would be immediately successful and that he was holding an emergency Cobra meeting with senior ministers and the governor of the Bank of England to discuss the economic impact of the conflict.
Iran has responded to Israeli-US missile strikes by effectively blocking the vital oil shipping lane of the Strait of Hormuz – a move which had pushed up oil and gas prices.
Sir Keir said he was looking at what support the government could offer in June, after the current energy price cap ends and in September, when households typically start using more energy.
He said Chancellor Rachel Reeves would make a statement in Parliament on Tuesday about the outcome of the Cobra meeting.
In an indication that the government might favour targeted support over more widespread help, Sir Keir said he was “acutely aware of how much it cost last time round” and that he was “acutely aware of the state of public finances”.
The prime minister appeared to be making a reference to the energy bill schemes introduced under the previous Conservative government, which aimed to limit prices rises following the Russian invasion of Ukraine.
Over the weekend, the government’s cost-of-living adviser Richard Walker urged the government to intervene by putting in place a temporary profit cap to stop energy and fuel retailers from exploiting the crisis to make profits.
Sir Keir said the government was “looking at measures to deal with profiteering” adding: “I think we might look at what further teeth we can give the CMA [Competition and Markets Authority].
“I think there isn’t enough regulation in this area.”
In a statement released following the Cobra meeting,, external Downing Street said there would be “a new anti-profiteering framework which will help regulators like the CMA to root out price gouging”.
Conservative leader Kemi Badenoch has urged the government to “drill the North Sea, cut carbon taxes and axe the fuel duty hike”.
Green Party leader in England and Wales Zack Polanski called for a “tighter oil and gas windfall tax, taxing income from wealth the same as from work, and double down on renewables and energy efficiency to protect us from future shocks”.
Speaking about UK involvement in the conflict, Sir Keir said “there must be a lawful basis and a viable and thought-through plan”.
He said that was “why we didn’t join the official strikes” but had allowed the US to use UK bases to strike Iranian missile infrastructure.
“This is not our war and we are not getting dragged into this war,” he said.