Alejandro Wolff, the acting US ambassador to the UN, said only amendments consistent with previous resolutions were retained.
Amendments "not in keeping with the architecture in place" were rejected, he added.
"Our proposals will be based on rights and laws and on the inalienable rights of all nations. Not only on what the US or Great Britain wants"
Mahmoud Ahmadinejad, Iran president
Mahmoud Ahmadinejad, Iran's president, said he would make new proposals to resolve the dispute but continued to reject demands to suspend uranium enrichment.
He has asked to speak before the council votes.
"Our proposals will be based on rights and laws and on the inalienable rights of all nations. Not only on what the US or Great Britain wants," Ahmadinejad told French media on Thursday.
The sponsors of the new draft added language underlining that the UN nuclear watchdog "is internationally competent for verifying compliance with safeguards agreements, including the non-diversion of nuclear material for non-peaceful purposes".
Dumisani Kumalo, South Africa's ambassador and this month's council chairman, described the changes as "cosmetic".
"We are disappointed because we made the amendments in good faith," he said.
"We expected they would give our capitals a chance to look at what they could accommodate... I don't know what is left for my minister to do."
"We'll meet tomorrow for one final consideration. But the text is in blue... "
Emyr Jones Parry, Britain's UN envoy
Emyr Jones Parry, Britain's envoy, said South Africa's proposal was rejected because it would have been "totally perverse" to "reward non-compliance of Iran's obligations".
"The only views which we have not taken account of are those which are so contrary to everything this council has done previously that we were totally unable to take them into account," he said.
"The text that we have submitted is one which we believe finds the centre of gravity of the debate," he added.
"It's an appropriate, proportional, incremental response to the situation."
On Saturday's voting, Parry said: "We'll meet tomorrow for one final consideration. But the text is in blue," indicating it was ready for an imminent vote.