Rescue ships must now request a port immediately after each individual rescue, instead of waiting to conduct more operations.
Italy's government has been criticised for introducing new rules that will limit the sea rescue capacity of NGOs and charities.
Rescue ships must now request a port immediately after each individual rescue, and sail immediately to it once it has been assigned.
Charities not abiding by the rules risk fines of up to €50,000 and could have their vessels impounded for repeat offenses.
Organisations that rescue migrants in the Mediterranean Sea say the measures will put lives at risk.
"We will be forced to leave the rescue areas unprotected with an inevitable increase in the number of deaths.,” Doctors Without Borders (MSF) wrote on Twitter.
"Since January, 1,360 people have lost their lives in the Central Mediterranean," it added.
Along with the new measures, Italian officials have been assigning ports further and further north, away from the migrant routes.
NGOs have also argued that more migrant boats will now be pushed back to African shores by the Libyan Coast Guard, where they will allegedly face torture, sexual violence, and extortion at the hands of guards in detention centres.
So far this year, more than 103,000 migrants have arrived in Italy, up 55% over last year, according to the Interior Ministry.