Chancellor Angela Merkel, president Emmanuel Macron and prime minister Giuseppe Conte issued a joint declaration on Saturday as they met in Brussels to discuss the coronavirus recovery package.
France, Germany and Italy said on Saturday they are prepared to impose sanctions on foreign powers violating the arms embargo in Libya.
"We call on all foreign actors to cease their interference and respect the arms embargo established by the United Nations Security Council", German chancellor Angela Merkel, French president Emmanuel Macron and Italian prime minister Giuseppe Conte said in a joint statement.
They said they are "ready to consider the possible use of sanctions if the violations of the embargo on the sea, on land and in the air continue", as they met in Brussels to discuss the coronavirus recovery package.
The three leaders also called "on all parties in Libya, as well as their foreign backers, for an immediate end to the fighting," expressing "serious concerns" at "the increase in military tensions in the country".
No specific country was mentioned in the release.
The issue had already been raised by the United Nations Secretary-General Antonio Guterres early in July, when he denounced "unprecedented levels" of foreign intervention in Libya, with "the delivery of sophisticated equipment and the number of mercenaries involved in the fighting".
Libya has been torn by a bloody civil war since 2011, following the end of a 40-year-long dictatorship by Muʿammar Gheddafi and his killing.
The country is contended by a UN-backed government, based in Tripoli and led by Fayez al-Sarraj, and marshal Khalifa Haftar, who currently rules over the eastern part of the country and some of the south.
Turkey supports Fayez al-Sarraj's government, while Haftar has the backing of neighbouring Egypt, the United Arab Emirates and Russia.