They struck at a property in Lane Cottages, Royson, between 6.30pm and 7.30pm on Saturday, January 13.
One of the robbers retrained one of the occupants while the other searched the property.
They left empty-handed.
A South Yorkshire Police spokesman said: "Between 6.30pm and 7.30pm on Saturday, January 13, it is reported that two unknown suspects with their faces covered forced entry to a property in Lane Cottages, Royston.
"One of the suspects is reported to have held one of the occupants while the other suspect searched the property.
"The pair then fled the scene empty-handed.
"The suspects are believed to be male and one of them is believed to have been carrying a metal bar.
"While the occupants, who are in their 70s, were not injured, they have been left shaken and upset by the incident.
"Do you live in the area? Did you hear or see anything suspicious?"
Anyone with information should call South Yorkshire Police on 101 quoting incident number 1,040 of January 13 or Crimestoppers on 0800 555 111.