Grossi addressed the matter during his opening remarks at a session of the IAEA Board of Governors in Vienna on Sunday.
He stated that in early May, the IAEA had installed surveillance cameras at Iranian facilities where centrifuge equipment is produced.
Additionally, he said the agency has installed monitoring devices at the Fordow and Natanz enrichment plants to oversee the level of uranium enrichment.
Iran had previously announced the presence of monitoring devices at the plants.
Grossi said that these measures would help the agency identify any changes in enrichment levels at those facilities.
Furthermore, the IAEA chief said Iran has provided its explanation about uranium traces that the agency had said were found at a site known as Marivan.
At a press conference after the BoE meeting, Grossi said the IAEA had received reasonable explanations from Iran in that regard but added that the agency would continue its investigations.
Grossi visited Tehran in March for high-level talks with Iranian officials, including with President Ebrahim Raisi, in an effort to resolve bilateral differences.
In a joint statement after the visit, the two sides agreed that interactions will continue in a spirit of collaboration and in full conformity with obligations under IAEA's Comprehensive Safeguards Agreement.