Mr Ashworth argued Conservative ministers’ insistence the proposals were not about making cuts meant Labour was not under an obligation to fund services saved by his plan.
But he admitted a Labour government could still allow changes to services to go ahead following a review.
Mr Ashworth used a speech in Batley to promise a Labour government would put plans to close accident and emergency departments and wider reorganisation proposals, known as sustainability and transformation plans (STPs), on hold.
The NHS is estimated to need to save £2bn in Yorkshire by 2021 although NHS England has said the STPs are not “all about saving money”.
Mr Ashworth told The Yorkshire Post: “These STPs are not about cutting NHS budgets. These plans are about redesigning local NHS services.
“They are not to save money, whenever you put that to Conservative ministers they will be every much insistent that STPs are not about cuts.
“They have said that in the House of Commons, [Health Secretary] Jeremy Hunt has said STPs are not about cuts.
“Given they are not about cuts, I don’t think therefore halting them has a spending implication.”
Mr Ashworth chose to deliver Labour’s pledge in an area which has seen major campaigns over moves to downgrade A&E services in Dewsbury and replace Huddersfield Royal Infirmary with a smaller hospital without an A&E department.
Batley and Spen is among a string of West Yorkshire seats Labour insiders fears they could lose next month if the Conservatives benefit from the swing indicated by opinion polls.
Mr Ashworth insisted Labour was not making “false promises” as he confirmed changes to services could go ahead following his planned review.
He said: “The principle of redesigning services is not necessarily a bad principle. The NHS cannot stay the same forever, populations change, technology changes and we all, I think, broadly agree now, that it is better to treat people in the community, in their homes.
“We are not setting ourselves against the principle of re-designing services, we are just setting ourselves against the principle of not involving the public and not involving clinicians.”
He added: “The promise we are making is to halt the proposals now and to review them properly and to involve the public.
“There will be examples across the country where people think it is reasonable to do what is proposed.”
Conservative Health Minister Philip Dunne said: “The simple truth is that Jeremy Corbyn can’t deliver his promises on the NHS – because his economic policies don’t add up.
“As we have seen today, there is a multi-billion pound black hole in Labour’s plans – that means less money for hospitals and staff.”
Liberal Democrat health spokesman Norman Lamb said the NHS needed “tough action on investment.
He said: “The original purpose of the STP process was a good thing – to bring fragmented parts of the system together.
“But it is based on the fantasy that there is enough money to deliver this vision, when the plans are now hundreds of millions of pounds short.”