Abdul Rahman, 40, was jailed this month for his conversion, and could have faced trial under sharia or Islamic law stipulating death as punishment for apostasy.
He was freed from prison on Tuesday after pressure from Western states whose troops helped bring the Afghan government to power.
"The release of Abdul Rahman was contrary to the existing laws of Afghanistan," Yunus Qanuni, president of the lower house of parliament, told the assembly during an unscheduled debate on the case.
"Abdul Rahman should not flee and should not be allowed to leave Afghanistan ... he should be kept under supervision," he said.
Storm of protest
Abdul Rahman's jailing raised a storm of protest in the West, with the US leading calls for his religious freedom to be respected and for him to be released.
His whereabouts were being kept secret to ensure his safety, officials said, but there was no indication on Wednesday he had left the country.
"The release of Abdul Rahman was contrary to the existing laws of Afghanistan. Abdul Rahman should not flee and should not be allowed to leave Afghanistan ... he should be kept under supervision"
Yunus Qanuni, president of the lower house of parliament
Afghanistan's Western-backed government has been seeking a way out of the crisis but has had to be mindful of conservatives demanding he be punished under Islamic law, and warning of trouble if he were not.
Several members of parliament said Abdul Rahman should not be allowed to leave but should be executed.
One member, who is also a cleric, said his release would provide ammunition to the government's enemies.
"This will pave the way for the opponents of the government to say war against the government is legitimate," said Abdul Aziz.
Qanuni said members of the Supreme Court and prosecutors should be summoned to parliament to explain Abdul Rahman's release.
The United Nations said Abdul Rahman had requested asylum abroad and it hoped one of the countries involved in the controversy would accept him.
Gianfranco Fini, the Italian foreign minister, said on Tuesday he would ask a cabinet meeting on Wednesday to offer Abdul Rahman "hospitality" in Italy.
Abdul Rahman became a Christian while working for an aid group helping Afghan refugees in Pakistan 15 years ago. He later lived in Germany before returning to Afghanistan.
He was detained after his relatives told authorities he had converted to Christianity following a dispute involving two daughters. Relatives later said he had suffered from mental problems, although he denied that.
Judicial officials had raised questions about his mental state and said he had to undergo psychiatric tests.