Defence Minister Yoav Gallant claimed on Monday that Iran has been building a runway that slices through forested mountains about 20km from Israel's northern border.
Mr Gallant, speaking at a high-profile security conference hosted by Reichman University near Tel Aviv, displayed satellite photographs that he said showed the site, where the Iranian national flag and the flag of Lebanese militant group Hezbollah could be seen.
Mr Gallant said Iran “is planning to act against the citizens of Israel", using the runway as a base.
Iran's mission to the UN did not immediately respond to a request for comment, AP reported. A representative for Hezbollah declined to comment on Israel's accusations. The Defence Minister did not specify when the satellite photos were taken.
The location he gave was near the hilly Lebanese city of Jezzin, across the border from the Israeli town of Metulla. Hezbollah this year invited journalists to watch a military exercise in a nearby town in southern Lebanon.
Satellite images from Planet Labs taken on July 28 showed work on a 1.2km runway, with four hangars constructed on tarmac to the east of the runway. Images from January showed the runway largely unpaved.
Israel has said in recent years that it has shot down Hezbollah or Iranian-linked drones launched from Lebanon and Syria.
Israel and Hezbollah fought a war in 2006. The border has remained tense but largely quiet since then, with both sides wary of another major confrontation.
But tensions have mounted. In an unusually bold attack this year, a man who Israeli officials said was probably linked to Hezbollah infiltrated Israel from Lebanon and detonated a bomb that severely wounded an Israeli citizen.
The group also allowed Palestinian armed groups to operate in its strongholds and fire rocket barrages towards Israel in the spring.
Israel has complained about further provocations by Hezbollah, including over tents it says the group pitched on the Israeli side of the Blue Line – a demarcation set by the UN for the purpose of confirming the Israeli withdrawal from southern Lebanon when it ended an occupation in 2000.
Mr Gallant did not describe how Hezbollah would launch attacks from the runway or use the airport for “terrorist purposes”.
He said that, in the event of a conflict, Israel would be prepared to strike Hezbollah with “deadly force” to ensure “Hezbollah and Lebanon pay a heavy price”.
Mr Gallant outlined what he said was a list of Iranian activities along Israel's various fronts, including support for militant groups in the Gaza Strip and occupied West Bank.
At the same conference, the head of Israel's Mossad spy agency on Sunday accused Iran of plotting deadly attacks against Israeli and Jewish targets around the world. David Barnea said Israel was prepared to strike perpetrators in “the heart of Tehran”.