Mr Annan met with Prime Minister Fuad Siniora, parliament speaker Nabih Berri and other politicians in Beirut on Monday, Lebanese officials said.
He pressed leaders on Lebanon's need to police areas along the Syrian border from where arms are suspected of being funnelled to Hezbollah from Iran.
He also stressed to Lebanese leaders that they, rather than the UN, must ensure the militia abides by the ceasefire, and refrains from any operations in southern Lebanon.
A Lebanese source said at the weekend that Mr Annan would underscore the need for "only the armed presence of Lebanese and UNIFIL soldiers" in Hezbollah strongholds in the south.
His visit comes as Hezbollah's leader Hassan Nasrallah said his fighters would not oppose UN forces deployed in southern Lebanon, but warned that the peacekeepers should not seek to take away Hezbollah's weapons.
"We have no problem with UNIFIL (UN Interim Force in Lebanon) as long as its mission is not aimed at disarming Hezbollah," Mr Nasrallah said in an interview aired on Sunday night on Lebanese television.
Nasrallah also said he regretted the capture of two Israeli soldiers that sparked the 34-day conflict.
"Had we known that the capture of the soldiers would have led to this, we would definitely not have done it," he said.
The two Israeli soldiers were seized during a July 12 Hezbollah cross-border raid that killed eight others.
Nasrallah said he would welcome a meeting with UN chief Kofi Annan and said contacts had been made toward that end, but added that nothing had been finalised for security reasons.
He also said negotiations on a prisoner swap with Israel had begun recently with Lebanon's parliament speaker Nabih Berri acting as an intermediary.
"Negotiations on a prisoner exchange began recently," he said, adding that Italy and the United Nations had shown interest in taking part in the talks. However, Israel later denied the claim.
Peacekeeping force
Mr Annan's visit follows Europe's pledge of up to 7,000 troops to form the core of a strengthened peacekeeping mission capable of enforcing the fragile truce between Israel and Hezbollah that took effect on August 14.
Half of the European Union troops are expected to be deployed rapidly, with some 200 French engineers and troops arriving at the weekend to pave the way for the larger UN deployment.
The UN deployment would take place within a week, the office of Israeli Prime Minister Ehud Olmert said late Sunday, quoting Mr Annan.
France, Lebanon's former colonial power, is to lead the force with 2,000 troops until February of next year, when it will be taken over by Italy, which is contributing up to 3,000 troops.
Mohammed Chatah, Mr Siniora's top adviser, told news agency AFP that Lebanon also planned to raise the issue of Israel's continuing sea and air blockade, which he said was a violation of UN Security Council Resolution 1701 and "is punishing the entire population".
"As far as Lebanon is concerned, Israel must withdraw immediately and without delay" from south Lebanon, he said.
He said Mr Siniora would also bring up the disputed Shebaa Farms district during his discussion with Mr Annan.
The territory, located at the junction of Lebanon, Syria and Israel, was captured by Israel as part of the Syrian Golan Heights during the 1967 war. It’s now claimed by Lebanon with the approval of Syria in an arrangement that is not recognised by the UN.
Mr Annan is also expected to visit Damascus and Tehran for talks.
Apart from Italy and France, Poland, Spain and Belgium have so far pledged troops to the peacekeeping effort. Several Asian countries are also expected to contribute.
Much of southern Lebanon lies in ruins after Israel's offensive against Hezbollah fighters that left at least 1,287 Lebanese, nearly all civilians, dead and 4,054 wounded.
About 160 Israelis, mostly soldiers, were also killed during the conflict.