The United Nations has launched a plan to bring stability to Libya through elections and changes to a 2015 political deal that set up a government of national accord led by Prime Minister Fayez al-Sarraj.
After two meetings were held in Tunis last year, there appears to have been little progress.
"The United Nations urges all Libyan actors to engage in earnest in an inclusive political process leading to credible and fair elections," said Feltman.
There is a "window of opportunity" to focus efforts on building unified state institutions, he added.
There was no immediate information on Feltman's meetings.
One of the main stumbling blocks is the inclusion in the new government of Khalifa Haftar, the powerful leader whose Libyan National Army dominates the country's east.