In an interview published overnight Wednesday, Hariri told the BBC that Israeli planes were entering Lebanese airspace every day, and he feared the prospect of another war with Israel.
He accused Israel of making a huge mistake by allegedly threatening both Lebanon and neighboring Syria.
"We hear a lot of Israeli threats day in and day out, and not only threats… We see what's happening on the ground and in our airspace and what's happening all the time during the past two months - every day we have Israeli planes entering Lebanese airspace," Hariri was quoted by the BBC as saying.
"This is something that is escalating, and this is something that is really dangerous," he said.
Hariri added that Lebanon was united, and that his government would stand by Hezbollah - the Lebanese terror group which fought Israel in 2006.
"I think they're (Israel) betting that there might be some division in Lebanon, if there is a war against us," he said, "Well, there won't be a division in Lebanon. We will stand against Israel. We will stand with our own people."
'We seek peace with Syria'
Syrian President Bashar Assad told Lebanese Parliament Speaker Nabih Berri on Sunday that Syria would support Lebanon in the event of any attack by Israel, the official Syrian news agency SANA reported.
“Syria will stand alongside the government and people of Lebanon against any possible Israeli aggression launched on Lebanon,” SANA quoted Assad as saying to Berri in Damascus.
Assad and Berri discussed “repeated Israeli threats on countries in the region and Israeli extremism which can kill chances of peace and bring war to the region,” SANA reported.
Israeli officials have warned repeatedly in recent weeks that any attack by Lebanon’s Syrian-backed Hizbullah would spark a tough response.
Syria and Israel have also been locked in a bitter war of words for several days.
Foreign Minister Walid al-Moallem warned on Wednesday that war against his country would become a wider conflict. “Israelis, do not test the power of Syria since you know the war will move into your cities,” Moallem said.
His Israeli counterpart Avigdor Lieberman retorted on Thursday that any war would cost Assad his grip on power. “When there is another war, you will not just lose it, but you and your family will lose power,” Lieberman said.
Israeli Prime Minister Benjamin Netanyahu sought to ease tensions on Sunday, saying that Israel wants peace with all of its neighbors.
“We made peace with Egypt and Jordan and we seek peace with Syria and the Palestinians,” he said.
AFP contributed to the report