The embassy cited “unforeseen circumstances” for Ghalibaf's inability to attend the meeting of speakers of parliaments from BRICS member countries.
However, an Iranian parliamentary delegation will participate in the forum, it said in a statement.
Ghalibaf's absence comes amid the conflict involving Iran, Israel and the United States, in which he has played a key negotiating role on behalf of Tehran, including on issues concerning the Strait of Hormuz.
Iran reaffirmed its commitment to participating actively in BRICS summits and meetings, saying its delegation would continue dialogue and consultations with other member countries to deepen bilateral and multilateral cooperation, particularly in parliamentary relations.
The embassy also thanked the Indian government for its hospitality and arrangements for hosting the meeting, and expressed hope that the forum would strengthen cooperation among member countries.
Birla had confirmed Ghalibaf's expected participation while addressing a press conference on Thursday to share details of the parliamentary forum.