David Cameron has told BP's chairman Carl-Henric Svanberg he is "frustrated and concerned" about the environmental damage caused by the US oil leak.
The UK PM said it was "in everyone's interest" the firm remained stable.
As much as 40,000 barrels (1.7m gallons) of oil a day may have been gushing from a blown-out well before it was capped on 3 June.
The US official overseeing the clean-up said the amount of oil being collected could be almost doubled by next month.
Oil has been leaking into the Gulf of Mexico since the Deepwater Horizon rig exploded on 20 April and sank off the coast of the US state of Louisiana, killing 11 workers.
A Downing Street spokesman said that in a phone conversation, Mr Svanberg told Mr Cameron that BP would "continue to do all that it can to stop the oil spill, clean up the damage and meet all legitimate claims for compensation".
Earlier, Chancellor George Osborne and senior officials met Mr Svanberg at Downing Street to discuss the crisis.
Mr Cameron is due to raise the issues in a call with US President Barack Obama at the weekend.
The spokesman said: "The prime minister had a constructive call with BP chairman Carl-Henric Svanberg.
"[Mr Cameron] explained that he was frustrated and concerned about the environmental damage caused by the leak but made clear his view that BP is an economically important company in the UK, US and other countries.
"He said that it is in everyone's interests that BP continues to be a financially strong and stable company."
'Vital British interest'
BP employs 10,105 people in the UK and it is estimated that about 18 million people in the UK either own BP shares or pay into a pension fund that holds BP shares.
BP's shares finished up 7.2% on the London Stock Exchange on Friday, recovering losses suffered on Thursday as the company came under pressure from the US administration to halt dividend payments and cover the full cost of the clean-up.
On Friday, the head of the US Coast Guard, Admiral Thad Allen - the US official overseeing the clean-up of the oil spill - said BP would be able to almost double the amount of oil it was collecting from the ruptured undersea well by next month.
He said once a "hard cap containment system" was in place, BP would be able to siphon off 50,000 barrels a day.
BP's chairman has been asked to meet Mr Obama next week, amid assurances from the UK and US that bilateral ties will not be affected by the crisis.
On Thursday, a former British ambassador to Washington, Sir Christopher Meyer, told the BBC that the government must "put down a marker with the US administration that the survival and long-term prosperity of BP is a vital British interest".
London Mayor Boris Johnson has expressed concern about the "anti-British rhetoric that seems to be permeating from America", but the government has downplayed the extent of such sentiments.