After a week on strike, union leaders had said they were ready to meet on Wednesday with managers of the northern Escondida mine, owned by Anglo-Australian giant BHP Billiton, and government mediators.
But the Escondida workers' union said in a statement that "scheduling problems" had prompted the company to ask for the talks to be postponed.
"There is no date set. These negotiations take time," junior labor minister Francisco Diaz said on T13 radio.
A source in the union told AFP that its leaders planned to meet with government officials on Thursday in the capital Santiago.
Some 2,500 workers are on strike at Escondida demanding a pay raise. They have warned the action could last up to two months.
The mine supplies five percent of global copper output -- some 927,000 tonnes a year.
Like other mining companies, the Anglo-Australian firm has had to cut costs as copper prices slid in recent years.
But prices have rallied in recent weeks on the back of US President Donald Trump's infrastructure spending plans.
Copper is a key component in wiring, and demand for heavy machinery, electrical grids and telecommunication networks drives prices up.
Renewed appetite in China, the world's biggest copper consumer, is also shaping the market.
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