The Brexit Party leader was also critical of the neighbour who made an audio recording of the argument between the Tory leadership front-runner and his partner, Carrie Symonds, but said it was in the public interest to discuss the claims because officers were called out.
Mr Johnson has faced days of unwanted headlines over the row at the south London flat after it was made public on Saturday.
Mr Farage said it was "appalling" that the argument was recorded and shared with The Guardian.
But he added: "Is it a matter of public record and public interest? Yes, it is, because the police were called, it's as simple as that.
"I'm actually astonished that he (Boris) didn't say police were called, in my view, maliciously by a neighbour looking to cause problems.
"I think that actually might have ended the story."
Mr Johnson's neighbour, Tom Penn, has defended recording the incident in the early hours of Friday before sharing it with the newspaper.
"Once clear that no-one was harmed, I contacted the Guardian, as I felt it was of important public interest," he said.
"I believe it is reasonable for someone who is likely to become our next prime minister to be held accountable for all of their words, actions and behaviours."
The Metropolitan Police attended the address but found "there were no offences or concerns apparent to the officers and there was no cause for police action".
Mr Farage said he would support Mr Johnson if he were to become prime minister and do "the right thing" over Brexit, but raised issues of trust.
Citing the former foreign secretary's record of rejecting Theresa May's deal before eventually backing it, Mr Farage said: "I'd love to know who the real Boris Johnson is and I would love to know what he really, really, truly believes."
Mr Farage added that a general election may be the only way to deliver Brexit.
"If Boris wins, it may well be that the only way to get Brexit, a clean Brexit, is to recognise this Parliament is never, ever going to deliver it and then call a general election on the issue," he said.
"If he did, I think he would win it by a very large majority."