Two Indian-flagged vessels carrying crude oil were attacked on Saturday while attempting to cross the Strait of Hormuz, India's Ministry of External Affairs confirmed in a statement.
India said it had called in the Iranian envoy to New Delhi and flagged its "deep concern" over the attack.
One of the vessels attacked was identified as the Sanmar Herald, an Indian government source said.
The crew on board and the vessel were safe, the source said.
India's top foreign ministry official asked the Iranian ambassador to convey India's view to Iranian authorities and to resume, at the earliest, the process of facilitating India-bound ships across the Strait, a statement from the ministry said.
The ambassador said he would convey these views to Iranian authorities, the statement said.
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