MPs Susan Kramer and Vince Cable want the proposed Royal Parks parking charges discussed in parliament.
They have asked for a debate on the fees for Richmond and Bushy parks within the next 30 days.
Dr Cable, who represents Twickenham, said: "There is a high level of opposition locally to the charges. They are unnecessary, petty, irrelevant to the Royal Parks' objective of reducing through traffic and will undermine the role of the parks as a place of relaxation, where residents are not harried by parking wardens and constantly clock watching.
"We shall use parliamentary procedures to put up as much opposition as we can. But the best way of stopping this proposal now is for both opposition parties to make it clear to the Royal Parks that the decision will be reversed in the event of a change of government."
John Karter, of the Friends of Richmond Park, said that while the group was not entirely against parking charges, they were concerned about the cost and impact of the proposals on nearby streets.
"The rates are too high and the cost will be prohibitive for many people - up to £1,000 a year for dog walkers who come to the park twice a day," he said. "We proposed a low-cost season ticket for regular park users, but this idea has been ignored.
"There will be a large increase in parking in those surrounding streets where parking is free, which will cause major difficulties for local residents. The elimination of a six-hour maximum stay will encourage commuters to continue parking in the park for the day."
Pieter Monpurgo of the Friends of Bushy and Home Parks, and the Keep Bushy Park Free Alliance, said he was disappointed with the decision.
He urged culture minister Margaret Hodge - who gave permission to charge up to £3 per visit to the parks - to consider alternative methods of raising revenue, such as charging a toll for those driving through.
In a letter to local MPs, Ms Hodge defends the charges. A disproportionate number of people from higher social groups visit the parks in their cars, she said.
She had decided not to impose the proposed six-hour maximum stay, claiming research suggested this could lead to people parking on nearby streets.
Royal Parks deputy chief executive Colin Buttery said: "At a maximum of £2 a day at Bushy Park and £3 a day at Richmond Park, the charges are similar to the cost of a cup of coffee. The fees compare favourably with car parks locally and at similar amenities."
Richmond Park MP Mrs Kramer urged campaigners not to give up their battle. "It is outrageous that the government is choosing to ignore the strength of opposition to these parking plans," she said.
"There is a long tradition of free access to the park, which will be lost if charges are introduced. I am also extremely concerned that the very real worries of residents about displacement of parking on to residential roads have not been taken on board. But the battle is not over yet. I will now be working with colleagues in parliament to try and force a vote on the plans.
"If the charges are introduced, the Liberal Democrats are already committed to trying to reverse the decision after the next General Election. We will be seeking this assurance from other political parties as we continue the fight."
The Conservatives' Richmond Park parliamentary candidate, Zac Goldsmith, said a protest rally organised for Saturday next week would still go ahead.
"The government has utterly failed to take into account the huge strength of local feeling," he said. "Thousands of people signed our petition.
"Richmond Park is one of the only places left where people can escape the hustle and bustle. That will change with these charges, and there will be many people who cut back on their use of the park to avoid them. The rally will absolutely go ahead as planned on January 30. It is vital that we get a big turnout. I believe we will."
The rally is at Pembroke Lodge in Richmond Park, starting at 10.30am.
