Hedi Annabi, the assistant secretary-general for peacekeeping, said such a move would help consolidate a cease-fire that took hold on August 14.
Under the UN resolution that ended the fighting, the international force in Lebanon should expand to up to 15,000 troops. But UN spokesman Stephane Dujarric said the UN had received no commitments so far.
"We hope to have a more formal meeting with the troop contributors on Thursday [August 17] in order to hopefully flesh out and firm up a number of offers," Dujarric said.
Meanwhile, Lebanese officials said 15,000 of their own troops would start deploying in the south in the next few days as Israeli forces withdraw.
Israel has warned displaced Lebanese not to attempt returning home until then, saying conditions were dangerous. But thousands of people have continued to stream back to southern Lebanon.