The foreign secretary was speaking just before chairing a meeting of the government's emergency Cobra committee.
Earlier Iran seized control of Stena Impero, a Brit-flagged tanker, which was carrying 23 crew but no British nationals.
As of Saturday morning, all 23 crew are still being held onboard, according to Iranian media.
A second Liberian-flagged but Brit-operated tanker, Mesdar, was raided by Iranian guards but released to continue its voyage.
And last night Mr Hunt has warned there would be "serious consequences" if the situation is not resolved quickly.
“If this situation is not resolved quickly there will be serious consequences”Jeremy Hunt, Foreign Secretary
He told Sky News: "We will respond in a way that is considered but robust and we are absolutely clear that if this situation is not resolved quickly there will be serious consequences."
Asked if he could rule out military intervention, Mr Hunt said: "We're not looking at military options - we're looking at a diplomatic way to resolve the situation - but we are very clear that it must be resolved.
"Freedom of navigation in the Gulf is absolutely essential. If that freedom of navigation is restricted, Iran is the biggest loser and so it is in their interest to resolve this situation as quickly as possible and we will do everything we can to do that."
The second ship - the Mesdar - was surrounded by 10 speedboats, Mr Hunt told Sky, though said it was "not clear yet" whether it had changed course.
He said he had spoken to US secretary of state Mike Pompeo this evening about the situation and had tried to speak to Iranian foreign minister Mohammad Javad Zarif but he is on a plane.
"I will speak to him as soon as I can", Mr Hunt said.
A leader British shipping magnate has warned this morning that the ongoing crisis of Iran could have huge impacts on oil and gas prices.
Bob Sanguinetti from the UK Chamber of Shipping told the BBC there "is no alternative route in and out of the Gulf," for the precious raw materials.
Around a fifth of global oil and a third of the world's gas supply passes through the Strait of Hormuz.
He went on: "If this is to endure then clearly it's going to impact on trade routes, trade patterns and ultimately the price of those goods going through the Strait because they are going to have to be sourced from elsewhere."
Donald Trump yesterday said Iran is “nothing but trouble" and the latest incident "goes to show you I was right about Iran".
He continued: "We will talk to the UK and we have no written agreement but we have an agreement. They've been a very great ally of ours.
"So we heard about it, we heard it was one, we heard it was two, and we will be working with the UK.
"They will have a new prime minister soon, which is a good thing, and we will be working with the UK - but we have no written agreement, but I think we have an agreement which is longstanding."