(Adds fresh Carney quote, background, paragraphs 3-6)
WASHINGTON, March 14 (Reuters) - Russia's failure to take steps to ease the crisis in Ukraine is "regrettable" and the United States is ready to respond quickly following a referendum planned for Sunday on whether Ukraine's Crimea region should join Russia, the White House said on Friday.
"We have obviously not gotten to a situation where Russia has chosen to de-escalate, where Russia has chosen a path of resolving the situation peacefully and through diplomacy. That is regrettable. We will have to see how the next several days unfold," White House spokesman Jay Carney told a briefing.
"We stand ready to respond should the referendum go forward on Sunday," Carney said. Asked how soon the response would come, he said, "I think without putting too fine a point on it, I'd say quickly."
Carney's comments came as U.S. Secretary of State John Kerry met with Russian Foreign Minister Sergei Lavrov in London in talks aimed at reducing tensions ahead of the planned referendum.
"We still hope that there is an avenue here that Russia will take in order to address its concerns in Ukraine in a manner consistent with international law, in a manner that respects the sovereignty and territorial integrity of Ukraine," Carney added.
"But there's no question that we're pretty late in the game here with regards to the situation and this referendum on Sunday," Carney added. (Reporting by Will Dunham and Roberta Rampton; Editing by James Dalgleish)