Recent comments by Obama have hinted at plans to make the UK- headquartered energy company pay the salaries of oil industry workers who have been laid off from other rigs since the April 20 disaster.
Those remarks have worried investors.
BP's share price fell to a 14-year low after the US threatened to impose new penalties on the company, angered by the magnitude of the spill caused by the collapse of a rig following an explosion.
'Ass to kick'
Obama has said he wants to know "whose ass to kick" over what has been declared the worst environmental disaster in US history.
Business leaders in the UK have criticised Obama for calling BP "British Petroleum", a name the company has not used for several years.
"Everyone is looking for someone to blame and BP is the ideal target. It is perceived as a foreign company," Peter Hitchens, an oil analyst, told Al Jazeera.
"That being said, BP is an international company. Around 40 per cent of its shares are owned by American people".
Following Saturday's phone call, Cameron's office said: "President Obama said to the prime minister that his unequivocal view was that BP was a multinational global company and that frustrations about the oil spill had nothing to do with national identity."
A spokesperson for Cameron described the phone conversation as "warm and constructive" and that the pair agreed to meet in person on July 20, when Cameron makes his first official visit to the US.
In Washington, a US senior official said Obama told Cameron that BP must pay "tens of thousands" of economic claims relating to the oil spill.
The leaders also reportedly discussed the war in Afghanistan, sanctions on Iran and the G20 meetings planned for later this month.