Pere Miro, who is in charge of relations with national Olympic committees, said "some officials" were not among those who arrived, which may avoid diplomatic embarrassment for Britain which is seeking to distance itself from the regime of President Bashar al-Assad.
Assad has drawn international condemnation over the escalating conflict with rebels, which has spilled into an all-out civil war.
"They arrived as planned and are ready to compete," Miro told Reuters. "Some officials decided not to come and that avoids a lot of problems."
Miro did not name individuals. In late June the BBC reported that Britain had refused a visa to the head of Syria's National Olympic Committee, General Mowaffak Joumaa, preventing him from attending the July 27-August 12 London Games.
There had been reports that some athletes might not want to compete for a country which is tainted in the eyes of many in the West and the region.
The international community has called for tighter sanctions against the Syrian government but Russia and China have stood in its way by vetoing a UN resolution.
Miro also said the president of Libya's Olympic Committee, freed on Sunday a week after being kidnapped in Tripoli by gunmen, would be attending the Games.
Nabil Elalem, a former Libyan judo champion, took charge of the Olympic body after its president Mohammed Gaddafi, one of the deposed dictator's sons, fled to Algeria last year.
"We spoke to him and everyone is very happy. He is trying to be here before the Games start," said Miro.