Speaking at a Cabinet session in Tehran on Sunday, Rouhani described the international spirit of solidarity with the Lebanese as signifying the vigilant conscience and sense of altruism and selflessness of contemporary humanity.
He also again expressed sorrow over the Beirut tragedy and on behalf of the Iranian government and nation sympathized with the Lebanese people.
The huge blast on Tuesday left at least 158 people dead and thousands of others wounded and in need of medical assistance.
Some 300,000 people were also displaced as residential buildings were fully or partially damaged.
Officials linked the blast to hundreds of tons of confiscated ammonium nitrate that were being stored in a warehouse at the port for six years.
The explosion has also destroyed Lebanon’s silos that contain the national grain reserve. Lebanon imports up to 80 percent of its food needs and is particularly reliant on imported soft wheat to make Arabic flatbread. About 85 per cent of the country's cereals were reportedly stored in the facility.