"We don't take steps backwards," Salvini told Italian broadcaster RAI.
The European Commission rejected Italy’s proposed budget for a second time on Wednesday, saying that the government of the far-right League and anti-establishment Five Star Movement had seriously violated fiscal rules.
The government has refused to alter its 2.4 per cent of GDP deficit target, which sits at eight times more than the previous government’s target.
Italy is planning to increase spending to deliver on campaign promises, which includes introducing a universal basic income, cutting taxes and lowering the retirement age.
But the EU commission has said that with the Italian government's current plan "we see a risk of the country sleepwalking into instability".
"Italy's draft budget plan is in particularly serious non-compliance [with EU debt rules]”, Commission Vice President Valdis Dombrovskis said in Brussels.
The Italian government now faces sanctions unless it refuses to comply with EU requests.
Italy could face an initial fine of 0.2 per cent of GDP, which would add a further €8bn to its financial debts.
The penalty could rise to 0.7 per cent if it still refuses to comply.
On Wednesday, Salvini said that any EU sanctions against Rome would be "disrespectful" towards Italians.
"We are convinced about the numbers in our budget," he told reporters.
“We will talk about it in a year's time."
It is widely suspected that Salvini is exploiting the situation to incite anti-EU anger before May’s European parliamentary elections.
European Commission Vice President Jyrki Katainen said on Thursday that it is wrong to see the case of Italy's budget as a showdown between Rome and Brussels.
"Yesterday we said what the Commission's opinion is [about the budget]," Katainen said.
"Now we are waiting to see what the member States say, but we don't want to encourage anyone to consider this a battle between the Commission and Italy."
