The White House said Thursday it's in "frequent communication" with European leaders over Greece's debt crisis, as U.S. stock markets took a tumultuous ride.

White House Press Secretary Robert Gibbs said that President Barack Obama had been working closely with his economic team as the Dow Industrials average plummeted almost 1,000 points this afternoon, before bouncing back somewhat.

"All I want to say is obviously the president has heard regularly from his economic team," Gibbs said, adding that Obama has "been in frequent communication, as they have been, with European counterparts."

Gibbs said he was not immediately aware of the sudden drop in the Dow and other economic indices shortly before 3 p.m. this afternoon, during his daily press briefing.

Republicans have demanded that no U.S. dollars go to bail out Greece, which European Union nations and the International Monetary Fund (IMF) are rallying to assist.

"The reforms that are needed to be enacted in Greece are important, and will take some time," Gibbs noted.

Update, 6:17 p.m.: Gibbs released a statement on Thursday evening outlining the president's actions to address the Greek debt crisis.

Obama met on Thursday afternoon with Treasury Secretary Tim Geithner and National Economic Council Director Lawrence Summers to discuss the situation, and spoke as recently as Sunday with Greek PM Papandreou to discuss the ongoing restructuring efforts in Greece.