"(Sunak) stressed that significant escalation was in no one's interest and would only deepen insecurity in the Middle East. This was a moment for calm heads to prevail," Sunak's office said in a readout of the call.

Sunak told parliament on Monday that the Group of Seven (G7) leading industrialised nations were working on a package of coordinated measures against Iran following the retaliatory missile and drone attack on Israel.

Italy, which currently holds the rotating presidency of the G7, said it was open to new sanctions for people engaged against Israel.

"The Prime Minister (Sunak) said Iran had badly miscalculated and was increasingly isolated on the global stage, with the G7 coordinating a diplomatic response," a Downing Street spokesperson said.

(Reporting by Alistair Smout; Additional reporting by Farouq Suleiman; Editing by Lisa Shumaker and Sandra Maler)