Four gunmen attacked the Pakistan Stock Exchange on Monday, killing two guards and a policeman before security forces killed the attackers.
The attackers were armed with grenades and automatic rifles, police said. They launched the attack by opening fire at the entrance gate of the Pakistan Stock Exchange in the southern port city, the country's financial center.
Heavily-armed special forces quickly surrounded the building and killed the attackers. The building is located in the heart of Karachi's financial district, where the Pakistan State Bank is located, as well as the headquarters of several national and international financial institutions.
In social media posts credited to the Balochistan Liberation Army, the terrorist group claimed responsibility for the attack.
Mousavi stressed that the only way to fight the root cause of terrorism is cooperation among all countries, especially regional states.
On Monday, an aide to Pakistan's prime minister on national security matters, Moeed Yusuf, and Foreign Minister Shah Mahmood Qureshi both said the attack was sponsored by hostile foreign elements.
Pakistani Prime Minister Imran Khan told Parliament on Tuesday he had “no doubt” that India was behind the attack on the stock exchange building in Karachi a day earlier.
Delhi rejected the charge on Monday, which External Affairs spokesman Anurag Srivastava said was an attempt by Pakistan to blame India for domestic problems.
IRNA, Reuters, and AP contributed to this story.