Barack Obama said the coordinated actions of the US and European Union would “have an even bigger bite” on Russia’s economy.
The new restrictions include banning Americans or people in the US from banking with three Russian banks.
The aim is to increase the cost to Russia of its continued support for pro-Moscow rebels in eastern Ukraine.
Moscow denies charges by the EU and US that it is supplying heavy weapons to the rebels.
Speaking at the White House, Barack Obama said the US was widening its sanctions to target the key sectors of the Russian economy – energy, arms, and finance.
“If Russia continues on this current path, the costs on Russia will continue to grow,” the president said.
The US Treasury said the banks being targeting in this round of sanctions were VTB, the Bank of Moscow, and the Russian Agriculture Bank (Rosselkhozbank).
Earlier, the EU also adopted new economic sanctions against Russia, targeting the oil sector, defense equipment and sensitive technologies.
Full details of the new EU sanctions are expected on Wednesday, when the EU is also set to name more Russian officials facing asset freezes and travel bans in Europe.
German Chancellor Angela Merkel, who had been reluctant to step up sanctions because of Germany’s trade links with Russia, said the latest measures were “unavoidable”.
Calls for the EU to act have been fuelled by the downing of flight MH17 over eastern Ukraine. All 298 people on the Malaysia Airlines jet were killed, many of them Dutch citizens.
An international team has again failed to access the crash site, amid heavy fighting between government forces and rebels there.
Western governments believe the pro-Russian separatists shot the plane down on July 17 with a Russian missile, believing it to be a Ukrainian military flight. The rebels and Moscow deny that, instead blaming the Ukrainian military.
Last weekend, the EU subjected a further 15 Russian individuals and 18 entities to asset freezes and visa bans for their alleged involvement in the Ukraine conflict.
The list of 87 targets of EU sanctions now includes the heads of the Federal Security Service (FSB) and foreign intelligence, the president of Chechnya, as well as two Crimean energy companies.
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