Mr Farage said the deal was “not Brexit” and insisted the Prime Minister agree to a ‘Leave alliance’ by the time general election nominations close on 14 November.
It follows reports that the Brexit Party was considering standing in as few as 20 target seats to avoid splitting the pro-Brexit vote and damaging hopes of a Conservative majority.
Mr Farage would not confirm if he personally was going to stand for election, saying he would make an announcement in the next few days.
He hit out at Mr Johnson’s "broken promises" after the government failed to take the UK out of the EU on 31 October, telling a press conference in Westminster: "I say to Boris Johnson - drop the deal."
The Conservatives have repeatedly rejected the Brexit Party's calls for an alliance, with a party source previously saying Mr Farage and Brexit Party supporter Arron Banks were "not fit and proper" to run the country.
Mr Farage told journalists his party had enough money for a "fully funded" election campaign, but that he was flexible to "local exceptions".
"Of course I'm open and flexible to local exceptions and already we are in communication with a number of MPs who are prepared to renounce the Withdrawal Agreement, to renounce the deal, and they themselves to stand on a ticket of a genuine free trade agreement or leave on WTO terms.
"And of course in those cases where MPs say this, we will view them as our friends and not as our enemies.
"And more interestingly, already we are being approached to put together informal arrangements on the ground - constituencies in which they may have a better chance of winning and we won't bother to campaign, but equally constituencies in which we have got a better chance of winning and they won't campaign and that is already beginning to come together.
"But that is not the real deal. The real deal is a Leave alliance that wins a big majority in Parliament. The real deal is a Leave alliance that delivers a genuine Brexit."