President Obama used a 30-minute phone call to reassure British Prime Minister David Cameron that his frustration over the leaking oil is not an attack on Britain.

According to the White House readout of the call, Obama and Cameron discussed the impact of the "tragic oil spill in the Gulf of Mexico, reiterating that BP must do all it can to respond effectively to the situation."

The tone of the conversation was "warm" according to Cameron's office. In recent days, Obama has sharpened his attacks on BP PLC as the British company continues to struggle to stop the oil from gushing into the gulf. Obama even said he would have fired BP's top executives if he were in charge of the company. He also embraced the idea that the oil company suspend its quarterly dividend. Those remarks did not come up, in the White House statement describing the phone call. And according to Cameron's office, Obama said he had no interest in undermining BP's value.

The Saturday chat is the first substantive conversation between the two leaders since Obama's congratulatory call to the new Prime Minister last month. Obama used the Saturday call to "affirm his deep commitment to the special and historic relationship between out two countries," the White House said.

For his part, Cameron has been under pressure to get Obama to tone down the criticism fearing it will hurt the millions of British retirees that hold BP stock. Cameron's office said the prime minister told Obama of his sadness at the disaster, while Obama said he recognized that BP was a multinational company, and said his frustration "had nothing to do with national identity."

The oil spill was not the only topic Obama and Cameron discussed. Iran and the World Cup also came up, according to the White House readout.

"The President thanked the Prime Minister for his commitment to lead on the broad range of issues on our shared agenda. The two leaders discussed Afghanistan, including the Prime Minister's recent visit, and they reaffirmed their firm commitment to NATO's ISAF mission. They discussed the decision by the United Nations Security Council to impose the strongest sanctions to date on Iran and the importance of follow-on action being taken at the upcoming European Council meeting, and they underscored the need for Iran to live up to its international obligations. They also exchanged views on economic issues, including preparations for the G-8/G-20 meetings later this month. The President and the Prime Minister discussed the impact of tragic oil spill in the Gulf of Mexico, reiterating that BP must do all it can to respond effectively to the situation. Finally, the President and the Prime Minister agreed to disagree on the desired outcome of the June 12 U.S.-England World Cup soccer match; the President noted that the historical record of previous World Cup matches between the United States and England favors the United States and the President wagered the best lager against the best beer in America on an American win over England."

Meanwhile, Cameron's office announced he will make his first visit to the United States as British prime minister on July 20.