"Extremism and terrorism have turned into a threat to all regional countries," Zarif said, urging further coordination, cooperation, and integration among the countries to counter such threats.
He made the remarks while speaking to reporters after meeting with Grand Ayatollah Ali al-Sistani, the top Iraqi Shiite cleric, in holy city of Najaf.
"Clerics and religious authorities have always had a constructive and prominent role in the fight against terrorism and extremism," Zarif stated, following the meeting.
He quoted the senior cleric as stressing the need for united and integrated efforts to establish peace and security in the region.
Zarif also said he briefed Ayatollah Sistani on the recent conclusion of nuclear talks between Iran and world powers, and conferred with him on important regional and international issues.
The Iranian foreign minister reaffirmed Tehran's support for the Iraqi government's efforts in the counter-terror campaign, and reiterated that "the Islamic Republic will continue to stand by Iraq in the fight against extremism and terrorism."
Zarif, who had earlier visited Qatar and Kuwait on the weekend, is in Iraq as part of his tour of regional states in a bid to explore avenues for bilateral, regional and international cooperation.