The global miner on Saturday said it has given workers until Tuesday to return and will offer a 2,000 rand ($179 or 231 euros) allowance if they do so.
But striking workers said they were not aware of the deal, which would signal a further winding down the strikes that have rocked platinum and gold mines.
“We know nothing about it. We were not consulted, we only heard about it on the radio,” said Amplats worker Reuben Lerebolo, carrying a poster stating “NUM we are tired of you”.
“We can’t go to work until our demands are met,” he said.
The moves to end the strike at Amplats comes as a strike in the gold mining sector also neared an end following a pay agreement between unions and mine operators.
However, Amplats CEO Chris Griffith said the agreement “does not mean that we have abandoned our current wage agreement or recognised negotiation structures and processes”.
The unrest has cost 10.1 billion rand ($1.2 billion, 912 million euros) in lost production since the beginning of the year, pushing the country’s yearly growth forecast downward to 2.5 percent.
The industry contributes up to nearly one fifth of GDP when related activities are included.
The strikes flared out of a deadly stand-off at Lonmin’s Marikana mine where police gunned down 34 people after 10 had died in clashes blamed on union rivalry.