Lord Cameron, who was made a peer in order to become Rishi Sunak’s foreign secretary last month, said Iran must be sent a clear message escalation will not be tolerated.
And he promised that Britain would work with allies to develop a strong set of deterrent measures against Tehran.
After a trip to France, Italy, Jordan and Egypt, Lord Cameron told the Telegraph: “Iran is a thoroughly malign influence in the region and in the world – there’s no doubt about that. You’ve got the Houthis, you’ve got Hezbollah, you’ve got the Iranian-backed militias in Iraq that have actually been attacking British and American bases, troops.
“And, of course, Hamas. So you’ve got all of these proxies, and I think it’s incredibly important that, first of all, Iran receives an incredibly clear message that this escalation will not be tolerated.
“Second of all, we need to work with our allies to develop a really strong set of deterrent measures against Iran, and it’s important that we do that. The level of danger and insecurity in the world is at an extremely high level compared with previous years and decades, and the Iran threat is a part of that picture.”
It comes as Iranian-backed Houthi soldiers have stepped up attacks on commercial shipping vessels in the Red Sea in recent weeks.
The Houthi rebels are understood to be targeting ships using the Bab el-Mandeb Strait, with the pro-Hamas group seeking to disrupt ships set for Israel.
Last week, oil giant BP became the latest major firm to pause shipping through the Red Sea over the attacks.
Lord Cameron summoned Iran’s most senior diplomat in the UK to the foreign office on Friday to “make clear these threats will not be tolerated”.
It comes amid growing concern in government at Iran’s increasing aggression on the world stage.
Grant Shapps also sounded the alarm over the deteriorating situation in the Gulf, with Houthis attacking commercial ships in the Red Sea.
The defence secretary said the UK would not allow the critical maritime route to become a no-go area.
In an interview with The Sunday Times, Mr Shapps said: “We are committed to protecting British interests [in the Gulf] – vessels sailing under a UK flag, or with British sailors or carrying goods destined for our shores.
“We have seen the disruption the terrorist attacks have caused — with major operators, including Maersk and BP, avoiding the region. We can’t allow any maritime area to become a no-go area, particularly such a vital route. But wider than that, we need to promote a safer world. The spate of illegal attacks represent a direct threat to international commerce and maritime security.”
He added that the “rules-based world order” means Britain must be committed to repelling the attacks and protecting global trade.