Prime Minister Fayez al-Sarraj "denies having asked Italy to send naval vessels into Libya's territorial waters... or fighter planes into Libyan airspace", his Government of National Accord (GNA) said in a statement late on Thursday.
"Such allegations... are without any foundation," Sarraj was quoted as saying in the statement. "Libya's national sovereignty is a red line that nobody must cross."
Tripoli and Rome had agreed to "complete its (Italy's) support programme for (Libya's) coastguard through training and armament to allow it to save migrants' lives and to confront the criminal (trafficking) gangs", Sarraj said.
The foreign ministry, in a statement carried by pro-GNA news agency LANA, said the Italian government had been asked "to provide logistical and technical support to the Libyan coastguard".
"This measure could require the presence of Italian ships in Tripoli port, only for this purpose and if necessary", the ministry explained.
The GNA chief, whose administration's control of the lawless country is limited, said he had also asked Rome "to support border guards" in southern Libya, the main entry point for migrants aiming to reach the shores of Europe, and to supply an electronic surveillance system.
Italy's Prime Minister Paolo Gentiloni said on Thursday that a government plan to deploy vessels in Libyan territorial waters to help fight human trafficking would be presented to parliament in Rome next week.
The cabinet was "discussing the details" of a request from Tripoli for assistance, he said.
Almost 94,000 people have been brought to safety in Italy so far this year, according to the Italian interior ministry, an increase of more than five percent compared to the same period last year.
More than 2,370 people have died since January attempting the perilous Mediterranean crossing, mostly on unseaworthy and overcrowded boats, the UN refugee agency says.