At 0738 GMT, the rouble was 0.16 percent stronger against the dollar at 65.37 and had gained 0.11 percent to trade at 73.40 versus the euro.

The rouble fell on Thursday towards its weakest levels since the first half of March, pressured by a warning from Standard & Poor's that new sanctions could trigger a rating downgrade.

However, the Russian currency was supported by a decrease in forex buying starting on Friday.

The Russian finance ministry said it would buy 11.6 billion roubles ($177.47 million) worth of foreign currency per day between April 5 and May 13, compared with 15.5 billion roubles a day in the previous period.

"The pressure on the rouble will drop slightly, which will partially protect it from the negative impact of news about the further U.S. restrictions," Andrei Kochetkov, an analyst at Otkritie brokerage, said in a note.

This week U.S. Republican and Democratic senators introduced legislation seeking to deter Russia from meddling in U.S. elections by threatening stiff sanctions on its banking, energy and defence industries and sovereign debt.

"Adding to the tense situation with Venezuela we get a weighty set of risks, which so far do not allow the rouble to reduce the current undervaluation," Mikhail Poddubsky, an analyst with Promsvyazbank, said in a note.

Brent crude oil, a global benchmark for Russia's main export, was down 0.39 percent at $69.13 a barrel.

Russian stock indexes were up.

The dollar-denominated RTS index was up 0.34 percent to 1,223.96 points. The rouble-based MOEX Russian index was 0.19 percent higher at 2,539.85 points.