"It's drifting on lack of real interest ahead of the Fed," said James Steel, chief metals analyst for HSBC Securities in New York, adding that the strong dollar also pressured prices.
Spot gold was down 0.3 percent at $1,105.00 an ounce, near Friday's one-month low of $1,098.35. U.S. gold futures for December delivery settled down 0.5 percent at $1,102.60 an ounce.
Spot silver was down 0.3 percent at $14.33 an ounce.
"This is a consolidation," said ING's head of commodity strategy, Hamza Khans. "People got long fundamentally, and are now taking profits off the table until they see how much volatility the dollar will introduce to the market."
Read MoreGold inches higher as Fed meeting nears
The U.S. dollar turned positive against a basket of major currencies as growth in domestic retail sales last month signaled solid consumer spending in the third quarter, which might encourage the Fed to lift interest rates on Thursday.
A small majority of forecasters are sticking to their guns and predicting the Fed will pull the trigger this week.
Stock markets edged up on Wall Street and Europe, while 10-year U.S. Treasury yields rose to a six-week high.
"The whole world is talking about the meeting on Thursday," MKS' head of trading, Afshin Nabavi, said. "We started at a 75 percent chance (of an increase this month), and now I've heard 25 percent. There is a lot of talk about next March, but we'll have to wait and see."
Industrial precious metals were buoyed by copper prices that rallied on late short-covering despite demand concerns in top consumer China.
Spot platinum was up 0.5 percent at $957 an ounce and palladium was up 2.4 percent at $600 an ounce.