President Obama announced Monday that he is leveling new sanctions against seven Russian officials the White House says have contributed to the crisis in Ukraine.

Obama announced the sanctions one day after the Crimean region of Ukraine voted overwhelmingly to join Russia in a referendum that the U.S. and western allies vowed not to recognize.

In comments at the White House to formally announce the sanctions, Obama said he believes there is still a diplomatic solution to end the crisis. At the same time, he warned that if Russia continues to interfere with Ukraine's sovereignty he stands ready to push for even tougher sanctions.

"We are imposing sanctions on specific individuals for undermining the sovereignty, territorial integrity and government of Ukraine," Obama said."We are making it clear that there are consequences for their actions."

The high-level government officials named by the White House are: Vladislav Surkov, Sergey Glazyev, Leonid Slutsky, Andrei Klishas, Valentina Matviyenko, Dmitry Rogozin, and Yelena Mizulina.

Surkov and Glazyev are presidential advisers to Russian President Vladimir Putin. The five others hold various positions in the Russian parliament and Russian government.

The punitive measure -- which will almost certainly heighten tensions between U.S. and Russia -- does not target Putin directly.

The sanctions focus on the individual personal assets, but not companies that the officials may manage on behalf of the Russian state. Any assets that the individuals have in U.S. jurisdiction have been frozen and Americans are prohibited from doing business with them.

In addition, the Treasury Department announced it is imposing sanctions against former President Viktor Yanukovych, former Ukrainian presidential chief of staff Viktor Medvedchuk as well as Crimea-based separatist leaders Sergey Aksyonov and Vladimir Konstantinov. Those officials were being targeted under an executive order that Obama signed earlier this month.

"The United States also will seek to hold accountable individuals who use their resources or influence to support or act on behalf of senior Russian government officials," the White House said in a statement. "We recognize that the Russian leadership derives significant support from, and takes action through, individuals who do not themselves serve in any official capacity. "

The White House announcement came after the European Union announced on Monday travel bans and asset freezes on 21 people for their involvement in the Ukraine crisis. The EU is not expected to announce the individuals who are being cited until Tuesday, but Obama administration officials believe there is some overlap in the U.S. and EU lists.

Crimeans voted overwhelmingly to secede from Ukraine and join Russia during Sunday's hastily arranged referendum.

Putin is expected to speak on the Crimea situation in a special address to the Russian parliament on Tuesday.

Obama spoke by phone on Sunday with Putin and reiterated that the United States would not accept the results of the referendum. He again called on Putin to support a diplomatic solution to the crisis, while underscoring that one cannot be reached if Russian troops continue to be deployed in Crimea.

Vice President Biden will visit Poland and Lithuania next week, where he is to huddle with leaders in the region on the Ukraine crisis. Obama will travel to the Netherlands next week to take part in the biennial Nuclear Security Summit, but the situation in Ukraine will be the main focus on the sidelines of the summit.

"If Russia continues to interfere in Ukraine, we stand ready to impose further sanctions," Obama said.