The Work and Pensions Select Committee found there was little evidence that lower payments would motivate disabled people to find work.
The allowance is set to be reduced from Â£102 to Â£73 per week from April.
Ministers have argued that savings would be invested in a new support package for the most vulnerable.
The committee said evidence supporting the idea that introducing a lower rate of Employment and Support Allowance (ESA) would enhance incentives to work was "ambiguous at best".
It welcomed a decision to make some severely disabled claimants exempt from repeated reassessment for ESA but said it had deep concerns about assessments proposed in the recent work and health green paper.
The committee said ministers should consider using incentives such as reductions in National Insurance contributions to encourage employers to employ people with disabilities.
Committee chairman Frank Field said: "We expect the government to respond to this report before the proposed new lower rate of ESA is due in April.
"If they intend to proceed with these cuts, we expect an explanation of how this will not be detrimental to its target of halving the disability employment gap, by making finding and keeping a job even more difficult for disabled people than it already is."
A Department for Work and Pensions spokesman said: "The number of disabled people in work has increased by almost 600,000 in the last three years, but we're determined to go even further.
"Our Work and Health Green Paper marks the next stage of our action to confront the attitudes, prejudices and misunderstandings that have become ingrained within the minds of employers and across wider society.
"Our welfare reforms are increasing the support and incentives for people to move into work, while keeping an important safety net in place for those who need it.
"In addition to ESA, we also offer support through Personal Independence Payments, to help with the extra costs associated with being disabled."
Cuts in disability benefits should be delayed until the government clarifies how it will support those in need of extra money, a group of MPs has said.