The official said Mahmoud Abbas, who has been in Tunisia this week, was expected to go to Libya but canceled because of security concerns. The official spoke on condition of anonymity because he was not authorized to talk to reporters.
Early Tuesday, a militia surrounded the building of the National Transitional Council in Tripoli. Abbas was supposed to meet NTC head Mustafa Abdul-Jalil there.
The Libyan government has failed to impose its authority on the country since the overthrow of longtime ruler Moammar Gadhafi last year. Militias control large parts of the country and the capital.