Immigration Minister Robert Jenrick says the government does not expect to make any new commitments on plans to remove people who come to the UK illegally.
The House of Lords has voted to strike down several parts of the Illegal Migration Bill, which ministers hope to pass before the summer recess.
The bill would place a legal obligation on the government to detain and remove those who come to the UK illegally.
It is key to Rishi Sunak’s attempts to stop small boat crossings.
Faced with strong opposition from the Lords, the government agreed to changes in the treatment of children and pregnant women.
Robert Jenrick defied critics of the government.
He told BBC Radio 4’s Today programme: “It’s not a serious or adult way to have a discussion to say ‘we don’t want this, we don’t want that’ and not propose an alternative.”
“The UK has the most comprehensive plan to tackle illegal immigration of any European country,” he said.
MPs are expected to reverse the changes made to the bill in the House of Lords, but the bill will then go back to the upper house.
The standoff continues and time is running out for the plans to be approved before Parliament’s summer vacation begins next Thursday.
The bill, backed by lawmakers in March, is central to Sunak’s high-profile pledge to “stop” small boats crossing the English Channel.
It would place a legal duty on the government to detain and remove to Rwanda or another “safe” third country those who arrive illegally in the UK.
The government says it is committed to its plan to expel the migrants to Rwanda, even though the Court of Appeal ruled it illegal. He has already said that he will appeal the decision in the Supreme Court.
There have been concerns about how children will be treated under the new immigration bill, as well as allegations that existing UK regulations to prevent modern slavery would be undermined.
Although the legal duty to deport immigrants would not apply to those under 18, the bill would give ministers new powers to deport them in certain circumstances and detain them for extended periods.
It would also extend the time limit children can be detained before applying for bail from three days to eight. An earlier version of the bill proposed allowing children to be detained without the ability to request bail for up to 28 days.
Additional reporting by Jasmine Andersson, BBC News