"The enemy is threatening us with a new war," Meshaal said at an Istanbul conference via video-conference from Doha, where he is based.
"We warn it [Israel] against seeking a fresh conflict," he said.
The Palestinians of Gaza, he asserted, "will remain steadfast and fight relentlessly".
Israeli officials have recently hinted at the possibility of launching a new war on the besieged coastal enclave, which since 2007 has reeled under a crippling Israeli embargo.
Meshaal went on to assert that Hamas had developed "the necessary tools for resistance".
"[Hamas] has built a professional army that has humiliated the Israeli army in previous confrontations," he said, referring to Hamas’ armed wing, the Ezzeddin al-Qassam Brigades.
In 2014, Israel launched a devastating 51-day military onslaught on the Gaza Strip in which more than 2,300 Palestinians were killed and tens of thousands injured.
According to Israeli figures, 68 Israeli soldiers and five civilians were killed in the conflict while 2,522 Israelis -- including 740 soldiers -- were injured.
Meshaal also stressed that Hamas continued to adhere to its longstanding political principles.
"Hamas has established a reputation for adhering to democratic principles and shura [consultation] in the group’s decision-making process," he said.
The Hamas leadership, he added, was responsible for "striking a balance between the national project [i.e., eliminating the Israeli occupation] without paying too steep a price, such as formally recognizing the occupier".
In regards to longstanding inter-Palestinian divisions, Meshaal blamed these partly on "external factors".
"But the internal factor is mostly to blame for fostering division and undermining reconciliation efforts," he said in a veiled reference to the Palestinian Authority (PA) of Palestinian President Mahmoud Abbas.
In April of 2014, Hamas and Abbas’ Fatah movement signed a reconciliation agreement calling for the formation of a Palestinian unity government tasked with overseeing Palestinian legislative and presidential elections.
The unity government was unveiled two months later, but it never assumed a governing role in the Hamas-run Gaza Strip.
Meanwhile, the relationship between Hamas and Fatah -- the latter of which leads the Ramallah-based PA -- remains beset by a host of outstanding differences.
"Yet despite the myriad challenges," Meshaal said, "our people have developed special capabilities and skills that have allowed them to maintain the fight against occupation".