The president discussed "ways to support a political transition to end the conflict" in Syria with British Prime Minister David Cameron, French President Francois Hollande, Italian Prime Minister Enrico Letta, and German Chancellor Angela Merkel, Xinhua quoted the White House as saying.
The leaders also discussed efforts to support the Libyan government to "enhance security and advance the political transition", the White House said.
The White House maintained in a statement Thursday that the Syrian government had used chemical weapons against rebels.
White House Deputy National Security Advisor Ben Rhodes also said that Obama has decided to provide "military support" to the Syrian rebels.
Obama will attend the G-8 summit scheduled for Monday and Tuesday in Northern Ireland.
Earlier, UN Secretary-General Ban Ki-moon reaffirmed his organisation's determination to seek a political settlement to the long-standing crisis in Syria, saying "there is no military solution" to the conflict.
"There is no military solution to this conflict, even if both the government and the opposition, and their supporters, think there can be," the secretary-general said.
"The military path points directly towards the further disintegration of the country, destabilisation of the region and inflammation of religious and communal tensions," Ban said.
The Syria crisis has claimed nearly 93,000 lives over the past two years. The crisis has also left 6.8 million people in need, and sent more than 1.5 million Syrians fleeing to neighbouring countries to seek refuge.