Hassan Nasrallah, leader of Lebanese militant group Hezbollah, has denied media reports that his health is deteriorating, Ahram Online reported.
"I have waited for a good opportunity to discuss the rumours that have appeared over the last two days, which are part of the media war against Hezbollah. Everything the people heard is totally incorrect," Nasrallah said during a speech on Wednesday reported by Egyptian state news agency MENA.
Nasrallah condemned growing Sunni-Shia tensions in Lebanon, describing them as "destructive" for the country's national interest and "unacceptable under all circumstances."
Speaking on Syria, Nasrallah denied there had been attacks by the rebel Free Syrian Army (FSA) on Hezbollah sites and an injury to Sheikh Naiem Kasem, a leading figure in Hezbollah.
Hezbollah is not in talks with the Syrian government to help end the 23-month uprising, Nasrallah said, nor is it providing military support to Syrian security forces.
Last Thursday, an FSA commander said his forces would target Hezbollah unless the latter stops shelling rebel-held territory.
General Selim Idriss, FSA chief of staff, told AFP on Wednesday that Hezbollah had long been taking part in hostilities in Syria, but had gone too far by shelling Syrian villages.
"Hezbollah is abusing Lebanese sovereignty to shell Syrian territory and Free Syrian Army positions," said Idriss.
"In the past week... Hezbollah has been shelling villages around Qusayr from Lebanese territory, and that we cannot accept."
The FSA had asked the Lebanese president and premier to intervene, said Idriss.
The office of Lebanese Prime Minister Najib Mikati has denied having any contact with the Syrian rebels.
Hezbollah has repeatedly denied sending fighters into Syria.
Hezbollah is preoccupied with preparations for an expected "confrontation" with Israel, Nasrallah said. "This is our main concern, and no one can alter our course now."
During a tour of Israel's southern border with Egypt in October 2012, Israeli PM Benjamin Netanyahu said Israel would "act with determination to defend its borders," just as "we thwarted Hezbollah's attempt" to penetrate Israeli airspace.
Netanyahu said a drone aircraft, which flew some 35 miles (55 km) into Israeli territory before being shot down, had been sent by Iranian-backed Hezbollah.