British warplanes took part in the strikes, which destroyed sites suspected of hosting chemical weapons development and storage facilities.
"There is no proposal on the table for further attacks because so far, thank heavens, the Assad regime has not been so foolish to launch another chemical weapons attack", Johnson said.
The EU's foreign ministers will formalise their support for the strikes, with ministers expected to declare they "strongly condemn the continued and repeated use of chemical weapons by the regime in Syria, including the latest attack on Douma, which is a grave breach of global law and an affront to human decency".
"It's very important to stress that this is not an attempt to change the tide of the war in Syria or to have regime change or to get rid of Bashar al-Assad".
"And I think one of the most distressing things about the events of the last few years is the growth, the contemptuous growth and use of chemical weapons in the Syrian theatre of conflict".
Britain and France on Saturday joined the US-led missile strikes, which came a week after a deadly attack on the town of Douma, where civilians were hit with chlorine and sarin, according to the Western powers.
"The Council is supportive of all efforts aimed at the prevention of the use of chemical weapons", says the draft conclusion of the summit published by Politico EU.
Yesterday Prime Minister Theresa May insisted the military action was "legal" and defended the decision to go ahead without securing the backing of Parliament.
"If even such a thing [a chemical attack] were to happen, then clearly, with allies, we would study what the options were", he added.
Despite describing the intervention as "successful", Britain's Foreign Minister said there were now no plans for further attacks.
He also did not rule out further attacks against Syria if the Assad regime continued the alleged use of chemical weapons.
"Let me be absolutely clear: we have acted because it is in our national interest to do so".
Britain sought "to alleviate further humanitarian suffering caused by chemical weapons".