Italy has accused India of violating international law on diplomatic immunity by preventing its ambassador from leaving the country.
Italy’s foreign ministry said this was an “evident violation” of the Vienna Convention on Diplomatic Relations.
Earlier on Monday, India’s Supreme Court said Italian envoy Daniele Mancini had waived his legal immunity.
The ruling came in response to Rome’s refusal to return two marines charged with murdering two Indian fishermen.
The marines were allowed to go home to vote in last month’s polls on condition that they return to stand trial.
Mr Mancini had given his personal assurance that the two marines – Massimilian Latorre and Salvatore Girone – would return within four weeks as ruled by the court.
India’s Chief Justice Altamas Kabir said on Monday the court had “lost trust” in the Italian ambassador.
He reiterated last week’s order for him not to leave the country “until further orders”. His next hearing is due to take place on 2 April.
The Italian foreign ministry said in its statement that it still hoped to find a solution “in the spirit of the friendly relations it wishes to maintain with India”.
The marines are accused of shooting the fishermen in Kerala in February 2012. They said they mistook them for pirates.
Italy wants its nationals to be tried in Italy. It believes India has no jurisdiction in the case because the incident took place in international waters.
But India has said that irrespective of the location of the ship, it has theright to try the marines¬†as the fishermen were unarmed Indians on board an Indian fishing boat.
In its ruling on Monday, the three-judge Supreme Court said Mr Mancini, who had negotiated the marines’ release, had waived his immunity by giving an undertaking to a court that the pair would return.
Prime Minister Manmohan Singh warned that “there will be consequences” unless Italy returned the marines.
In unusually strong language, the prime minister said Italy’s refusal to do so was “unacceptable”.