Britain's Prime Minister Keir Starmer gestures as he answers questions during a visit. AFP
"We are engaging with our US counterparts to work through the detail," the spokesman said after Trump signed executive orders to impose 25 percent tariffs on steel and aluminium imports from March 12.
"It's obviously important that we take a considered approach to this ... This government is clear that we will always work in our national interests," he said.
"We're resolute in our support for the (British) steel industry," the spokesman added.
Canada, Mexico and Brazil are among the biggest steel exporters to the United States, followed by South Korea.
Britain exports about 10 percent of its steel to the US, shipping nearly £400 million ($495 million) worth there in 2023.
Britain's steel industry body on Monday called the tariff plan a "devastating blow", as the country's new ambassador to the US, Peter Mandelson, expressed his concern.
"I'm going to focus, in a laser-like way, on the dialogue between us to make sure that we do not become collateral damage in the US," Mandelson told the BBC on Monday, his first day in the role of ambassador.
"We actually have a very balanced trade relationship between Britain and the US. I don't believe that his tariffs are actually directly targeted at us," he added.
He said the UK should not be "overreacting" to events, and needed to respect Trump's "strong and clear mandate for change".
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