Speaking on the Andrew Marr Show, the foreign secretary said the primary objective of taking action was "to say no to the use of barbaric weapons".
"In this context, the Council understands the targeted US, French and United Kingdom airstrikes on chemical weapons facilities in Syria as septic measures having been taken with the sole objective to prevent further use of chemical weapons and chemical substances as weapons by the Syrian regime to kill its own people".
It came in response to a suspected chemical weapons attack on the rebel-held city of Douma a week earlier which claimed the lives of 75 people, including young children.
"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 Foreign Secretary, however, admit the civil war in Syria will continue in its "horrible, miserable way", as he entered a meeting of the European Council's foreign ministers in Luxembourg.
"I'm afraid the Syrian war will go on in its frightful, miserable way".
"If even such a thing [a chemical attack] were to happen, then clearly, with allies, we would study what the options were", he added.
"The erosion of that taboo, that has been in place for 100 years, has gone too far under Bashar al-Assad and it was time that we said "no" and I think it was totally, therefore, the right thing to do".
Prime Minister Theresa May is expected to face a backlash on Monday when she addresses parliament, which will be followed by an emergency debate, with some MPs angry the government joined the US-led mission without first seeking their approval.
Labour is calling for a "War Powers Act" that would enshrine in law the need for the Government to seek Parliamentary approval before launching military action.