"There are some important issues still on the table and there is no resolution at this point," said Mr Spicer.
US President George W Bush, who arrived in Russia on Friday after talks with German Chancellor Angela Merkel, has said he intends to press summit host Vladimir Putin on Russia's record on opposition parties and the media.
The three-day summit, which officially begins on Saturday and will bring together the leaders of Britain, Canada, France, Germany, Italy, Japan, Russia and the United States, is mainly expected to focus on energy security, terrorism and the escalating situation in the Middle East.
Leaders of the world's major developing nations, including China, India and South Africa, are also expected to attend the summit.
The lack of progress on the stalled world trade talks, the so-called Doha Round, which are aimed at improving market access for poor countries, are expected to be the centrepiece of discussions with developing country leaders.