Labour Party MPs also put pressure on Prime Minister Gordon Brown to rethink planned fuel and road tax increases, prompting ministers to hint at a possible about-turn.
Drivers from across Britain converged on the capital in convoy, closing a busy artery and causing traffic backlogs. Similar protests took place in Wales, in a new headache for Brown whose leadership is under fire.
The drivers said fuel bills had risen by almost half in a year and demanded a rebate. French truckers threatened similar action.
Ministers, anxious after voters punished Labour in recent local elections, said they were listening to concerns.
There was no sign Brown would give in to the truck drivers but ministers said they would keep an "open mind" on a planned hike in vehicle excise duty that will hit families squeezed by rising fuel and food costs.
"We've made it clear we'll go ahead with the announcement we've made but we've also made it clear, and this is not contradictory, that we have an open mind in the future," environment minister Phil Woolas told BBC Television.
Woolas said a proposed two pence per litre rise in fuel tax, already postponed by six months to October, would be reviewed again in October as planned.
Justice Secretary Jack Straw earlier hinted at a possible policy change, telling BBC Radio: "The chancellor and the prime minister say they are listening to public concerns and if there are going to be decisions, they could be made in the autumn."
Newspapers confidently forecast a government "U-turn" on the vehicle tax.
The truckers argued they were essential to keeping the nation moving and that many businesses were at risk of closure.
