Strong oil prices, however, limited losses.
The central bank's decision to keep its key interest rates unchanged had no market impact as it was widely expected and had been already priced in.
By 1328 GMT the rouble eased 0.8 percent to 31.91 against the dollar , heading away from its strongest level since May of 31.42, hit on Thursday.
Versus the euro, the rouble shed 0.3 percent to 39.11. It weakened 0.5 percent to 35.15 versus the euro-dollar basket.
"The market is thin and profit taking in risky positions is going on ahead of the weekend," said Stanislav Yarushevichus, chief dealer at ING in Moscow.
"Players keep on locking in profits as there is a feeling that higher oil prices have been already priced in and now people expect markets to turn lower," said a dealer at a Western bank in Moscow.
Prices for Brent crude held above $112 per barrel after recovering from levels of around $100 seen a month ago, lending support to Russian assets.
Risk aversion rose globally after China's export and import growth came in well below expectations in July, weighed down by weakness in major trading partners and lower commodity prices.
"The rouble got under pressure from China's data ... But high oil prices will restrain the rouble's weakening," said Pyotr Neymishev, chief dealer at Otkritie Bank.
Dealers see the market remaining volatile with the basket trading around 35 roubles on average if oil prices stay above $100.
Russian stocks were also hit by risk aversion, with the dollar-traded RTS index falling 2.1 percent to 1,416.9 points. The rouble-based MICEX index was down 1.4 percent at 1,435.9 points after rising for six days in a row.
"The big move has already happened and now it's unclear what's next. We try not to carry positions from one day to another. Shares have been already fairly priced by the market," said a trader at a Western bank in Moscow.
If the MICEX index breaks through support of 1,430 points, the next support level could be found at 1,415, which is a 21-day moving average, analysts at Alor said in a note, adding that resistance lies at 1,450 points.
Shares in Novatek fell 1.7 percent after Russia's top non-state gas producer reported a 33 percent drop in the second quarter net profit.