"Hezbollah's press bureau wishes to clarify that what was published Wednesday in the As-Safir newspaper did not appear in the text delivered by the deputy secretary-general of Hezbollah," the group said in a statement.
The denial came after the newspaper quoted Qassem as saying in an address: "We now have a trained army and the Resistance (Hezbollah) does not need to rely on guerrilla tactics."
As-Safir's article came after images shared widely on social media showed Hezbollah conducting a military parade in Syria, where it is fighting to bolster President Bashar al-Assad's forces.
The images provoked controversy in Lebanon, where the Shiite movement is a divisive force, as well as concern from Washington, which deems Hezbollah a "terrorist" group.
The group said its denial also invalidated a previous "clarification" in which its press office told AFP that Qassem's quote was in fact: "We have become more than a guerrilla movement but less than an army."
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Hezbollah staged the military parade in the town of Qusayr, which it retook the town from Syrian rebels in 2013 in its first major victory after it intervened in support of Assad's regime earlier that year.
Photos of tanks, armoured vehicles and anti-aircraft batteries displaying the Shiite movement's yellow flag have appeared on social media in recent days.
Hezbollah's militia never disarmed after Lebanon's devastating 1975-90 civil war and is the country's most powerful armed force.
Detractors accuse it of being a "state within a state" and Washington has designated it a "terrorist" group since 1995, accusing it of a long list of attacks including the bombing of the US embassy and Marine barracks in Lebanon in 1983.
Washington supplies equipment to Lebanon's army and a State Department spokeswoman said this week that the US would be "gravely concerned" if it ended up in Hezbollah's hands.