Israeli Education Minister Naftali Bennett said that the results of the Lebanese election "strengthen what has been our approach for a while: Hezbollah=Lebanon".
Formed in the 1980s to fight against Israel, Hezbollah now battles in Syria alongside President Bashar al-Assad's forces.
"The make-up of the new legislative chamber represents a guarantee and a great strength to protect this strategic choice and to protect the golden equation - the army, the people and the resistance", Nasrallah said.
If confirmed by the final count, this result would boost Hezbollah politically, with parties and individuals aligned with the heavily armed group securing a simple majority in parliament.
The scene of a terror attack at the entrance to Ariel in the West Bank
On Sunday, Lebanon held its first general election since 2009.
The election was held under that law adopted past year, which was expected to give Hezbollah a majority in parliament.
"After nine years, now it's the first time for the Lebanese to participate in this election, and to have the possibility to change or to continue the process of peace and democracy in Lebanon, and the Middle East as well", Risk said.
As many as 976 candidates competed for the 128 seats in parliament, which are distributed according to the ethnic-confessional principle between 11 groups.
Hezbollah, which was created in the 1980s to fight against Israel and now battles in Syria alongside regime forces, is listed as a terror organisation by the United States, while the European Union lists Hezbollah's military wing as a terrorist, differentiating between its military activities and political.More news: Wall St mixed as Fed seen on track for June hike
The new law redrew constituency boundaries and changed the system from first past the post to proportional representation in an attempt to encourage voting.
A higher turnout than the 49.2 percent announced overnight had been expected after the long electoral hiatus but the new pre-printed ballots used Sunday appeared to confuse some voters.
Lebanese daily Al-Akhbar, which is staunchly pro-Hezbollah, described the election as "a slap" for Hariri on its front page. Hezbollah has also backed Syrian dictator Bashar al-Assad in the country's civil war while its interference in countries like Yemen and Syria has earned it the terrorist label from a number of oil-rich Gulf nations.
Among the Christians, the right-wing Lebanese Forces party did particularly well, appearing to nearly double its number of seats from eight to 15.
The group, according to the unofficial results, added one seat and now has a bloc of 13 in parliament, known as "Loyalty to the Resistance" bloc.More news: Donald Trump denies he is changing his story on Stormy Daniels payment
In Zahle, Lebanon's third largest city, the predominantly Sunni Muslim Future Movement joined forces under one list with traditional political opponents, the Christian-Maronite Free Patriotic Movement, founded by the country's president, Michel Aoun. He is the scion of a famous political dynasty and son of late former prime minister Omar Karame, who was an ally of Damascus.
Other regional dynamics affected the vote.
The preliminary results show at least one candidate from a civil society list - journalist Paula Yaacoubian - won a seat in the capital Beirut, an area traditionally monopolized by established political parties.
Mr Hariri blamed the reduced turnout on the complexities of the new electoral law.
"The problem with this election: a lot of people didn't understand it", he said when asked about the turnout.More news: 'Avengers: Infinity War' now fastest film to earn $1 bn worldwide
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