In a meeting with visiting Afghan President Ashraf Ghani in Tehran, President Rouhani warned against the threat of narcotics production and trade to both the Iranian and Afghan nations.
He urged "consultation and coordination" between Tehran and Kabul in order to bring about a shift in the cropping pattern in Afghanistan and introduce new agricultural produce as alternatives to opium poppy.
"The Islamic Republic of Iran is ready to provide Afghanistan with any kind of help in changing the cropping pattern," Rouhani stressed.
He also underlined the need for stronger cooperation in the fight against narcotics trafficking.
Ghani, for his part, said the war on illicit drugs should take account of both the economic and security aspects.
In December 2014, the United Nations reported a 60% growth in Afghan land used for opium poppy cultivation since 2011, up to 209,000 hectares. The estimated $3 billion value of Afghan heroin and morphine represents some 15% of Afghan GDP.