Foreign Ministry spokesman Bahram Ghasemi was quoted by the state-run IRNA news agency today as rejecting the "baseless and fake claims" and "childish finger-pointing" from Bahraini authorities.
Bahrain has been combatting a low-level insurgency since the Sunni monarchy quashed a 2011 Arab Spring uprising led by majority Shiites.
Bahrain's interior minister, Sheikh Rashid bin Abdullah Al Khalifa, said yesterday's blast was "the latest example of a terrorist act performed by terrorists in direct contact with and under instruction from Iran."
Gulf tensions have intensified in recent days after Sunni-led Saudi Arabia blamed Shiite Iran for a ballistic missile fired by Yemen's Shiite rebels that was intercepted near Riyadh. Iran has denied any involvement.