Cameron, Obama, French President Nicolas Sarkozy and German Chancellor Angela Merkel discussed the crisis by videoconference as Europe's leaders struggled to build a lasting solution to the continent's debt crisis, which has roiled global markets for months.
A White House statement issued after the videoconference said that "Chancellor Merkel and President Sarkozy fully understand the urgency of the issues in the eurozone."
In the most effusive praise so far for European efforts to beat the debt crisis, the statement said the leaders were "working diligently" towards a "comprehensive solution" which will be "politically sustainable."
The praise came even though rifts over the package – aimed at corralling Greece's debt problems, strengthening banks and expanding the EU emergency rescue fund – remained evident Thursday.
After having originally promised to G20 allies that decisive action would be taken at this weekend's summit, more wrangling between Paris and Berlin has made it clear a deal won't be finalized.
Leaders are now planning a followup meeting sometime next week.
"We have made enormous progress but not enough to take final decisions on Friday," said Steffen Seibert, spokesman for Merkel. "We will have talks on Sunday and we will take decisions on Wednesday," he said.
Obama has been involved in frequent transatlantic calls in recent weeks, after warning that the European debt crisis poses significant risks to the slowly recovering US economy.
Meanwhile Treasury Under Secretary Lael Brainard said the US sees Europe's leaders are "intensively" tackling the issues they need to.
"Europe has the resources, it has the capacity and we have heard from European leaders that they have the will," Brainard told a Senate committee. "The set of issues on the table is the right set of issues," she said, adding: "They will need to move forward."
The White House said the four leaders agreed to continue consulting closely before they meet up at the G20 summit in Cannes, France early next month.