"The secretary-general is deeply concerned by this upsurge of violence across Pakistan," Xinhua quoted a statement by Ban's spokesman on Monday.
"While acknowledging the measures already taken to maintain security, he urges the government of Pakistan to further increase its efforts to address terrorism and religious extremism, including the protection of rights to safely practice religion, and to bring the perpetrators of such attacks to justice," the statement said.
The attack on Jinnah International Airport in Karachi began on Sunday night when at least 10 heavily armed militants disguised as security forces stormed the terminal building and opened fire at security personnel.
Tehreek-i-Taliban Pakistan claimed responsibility for the attack
The Tehreek-i-Taliban Pakistan on Monday claimed responsibility for the attack that killed at least 23 people, saying that it was launched in retaliation for military operations on their hideouts in the northwestern tribal areas of the country.
In another incident, suicide attacks against Shia pilgrims killed at least 24 people in Balochistan province.
Officials said the attackers hurled two hand grenades at two buses parked outside a hotel in Taftan area of Chaghi, a district near the Pakistan-Iran border.
"The secretary-general expresses his solidarity with the government and the people of Pakistan and extends his deepest condolences to the families of the victims," the statement said.