DGCA asks all Indian airlines to avoid affected Iranian airspace

The aviation regulator of the US, the Federal Aviation Administration, has already prohibited all its airlines and commercial operators from flying over the Persian Gulf and the Gulf of Oman.

British Airways, KLM, Malaysia Airlines, Singapore Airlines, Lufthansa among others are also avoiding flying over the region.

Early Thursday, Iran shot down the RQ-4A Global Hawk drone of the US. This immediately escalated tensions in the region which is grappling with crippling sanctions after the US withdrew from Iran's 2015 nuclear deal. The drone was a high-altitude robot used for surveillance over the ocean and coastal regions.

United Airlines has also decided to suspend service between India and Newark until September 1. United operated direct flights connecting Newark to Delhi and to Mumbai.

"Given current events in the Middle East and the continued closure of Pakistani airspace, we have decided to suspend our service between India (Mumbai and Delhi) and Newark until September 1," United said in an email response to a query from CNBC-TV18.

The US aviation regulator also warned pilots that flights are not permitted in the overwater area of the Tehran Flight Information Region until further notice, "due to heightened military activities and increased political tensions that might place commercial flights at risk," adding that these military activities and political tensions present an inadvertent risk to US civil aviation operations and potential for miscalculation and misidentification.