The Syrian ambassador's invitation to Friday's royal wedding has been withdrawn after UK officials said it was "inappropriate" for him to attend.
The decision to invite Dr Sami Khiyami had been criticised, amid condemnation of a violent crackdown on pro-democracy protesters in his country.
The Foreign Office said his presence would be "unacceptable" and that Buckingham Palace "shared that view".
Dr Khiyami described the decision as "a bit embarrassing".
The Foreign Office summoned him earlier this week to urge his government to end the violence, in which a reported 400 people have been killed, and grant more political freedoms.
Amid a growing row over Dr Khiyami's invitation to the wedding of Prince William and Kate Middleton, the Foreign Office said representatives of countries with which the UK had "normal diplomatic relations" had been invited.
But in a statement, it added: "An invitation does not mean endorsement or approval of the behaviour of any government, simply that we have normal diplomatic relations with that country.
"In the light of this week's attacks against civilians by the Syrian security forces, which we have condemned, the foreign secretary has decided that the presence of the Syrian ambassador at the royal wedding would be unacceptable and that he should not attend.
"Buckingham Palace shares the view of the Foreign Office that it is not considered appropriate for the Syrian ambassador to attend the wedding."
Asked about the development, which Downing Street said had followed discussions between the Foreign Office and the royal household, Prime Minister David Cameron said the "right decision was made".
Dr Khiyami said he had yet to decide whether to attend the wedding when he learnt the invitation had been withdrawn.
He told Radio Four's World At One: "I found it a bit embarrassing but I don't consider it a matter that will jeopardise either ongoing relations or discussions with the British government."
He added: "I don't really understand it but I understand the influence of media on the government decisions."
The ambassador also expressed sympathy for Prince William and Kate Middleton.
"The bride and groom need not have their wedding distracted by other matters," he said.
For Labour, shadow foreign secretary Douglas Alexander said: "William Hague took the right decision this morning to withdraw the invitation to the Syrian ambassador."
He added: "It's crucial at this stage that we send a clear and unequivocal message to the regime in Damascus...
"It [Dr Khiyami's presence] would also have distracted from the national celebration that will be the royal wedding on Friday."
A number of Labour MPs, including former Foreign Secretary Jack Straw, had expressed concerns about the invitation and it had been contrasted with the decision not to invite former Labour prime ministers Gordon Brown and Tony Blair.
Asked about the issue before it was confirmed that the invitation had been rescinded, Deputy Prime Minister Nick Clegg said who attended the royal wedding was a matter for the Royal Family, not the government.
But he added: "I think the events in Syria are clearly the subject of huge concern, people are going to be very, very distressed and appalled by the heavy handed military tactics which the Syrian regime are now deploying on their own people."
Speaking during a visit to Colombia, Mr Blair said he did not mind missing the wedding.
He said it was "not a problem at all" and wished William and Kate every happiness.
A spokeswoman for Mr Brown said: "Gordon and [Mr Brown's wife] Sarah both wish Prince William and Kate Middleton every happiness for the future.
"They will be joining in celebrating their marriage like all of Britain and lots of people around the world."
Some 200 members of Syria's ruling Baath party are reported to have resigned over the violent crackdown against pro-democracy demonstrations in cities across the country.
President Bashar al-Assad's government disputes the Western view that the protesters have been non-violent. It has said it sent troops to several cities on the request of citizens who were worried about "armed extremists".
There has also been criticism of royal wedding invitations extended to other diplomatic representatives.
The Crown Prince of Bahrain, whose country has recently clamped down on pro-democracy protests, was invited to Friday's wedding.
He pulled out at the weekend so as not to overshadow the event.
But the Foreign Office said it had no plans to withdraw the invitation to the ambassador of Bahrain, which has been under martial law since the middle of March, although it stressed this did not indicate it endorsed his government's behaviour.
It also confirmed that Libya's ambassador had been officially invited but was not expected to attend.
BBC royal correspondent Peter Hunt said representatives from Zimbabwe, Iran and North Korea were among the 2,000 people who had been invited to Westminster Abbey and were expected to attend.
More than 200 of the guests will be drawn from the ranks of government and Parliament as well as the diplomatic corps.