Iran's supreme leader Ayatollah Ali Khamenei said "enemies" were trying to drive a wedge between Tehran and Baghdad in a tweet on Monday following deadly unrest in neighbouring Iraq.
"#Iran and #Iraq are two nations whose hearts & souls are tied together... Enemies seek to sow discord but they've failed & their conspiracy won't be effective," Khamenei was quoted as saying on his office's Twitter account.
State news agency IRNA said the supreme leader was reacting to recent violence in Iraq.
More than 100 people have been killed in Iraq since clashes erupted last week between protesters and security forces, the majority of them demonstrators struck by bullets.
The Iraqi authorities have accused "saboteurs" and unidentified snipers of targeting the protesters.
Iran has urged its citizens planning to take part in a major Shiite pilgrimage in Iraq to delay their travel into the country over the violence.
Tehran has close but complicated ties with Baghdad, with significant influence among its Shiite political groups.
The two countries fought a bloody war from 1980 to 1988 and Iran's influence in the country grew after the US-led invasion of Iraq toppled veteran dictator Saddam Hussein in 2003.
(Except for the headline, this story has not been edited by NDTV staff and is published from a syndicated feed.)