Mohsen Rezaei's comments to Iran's state broadcaster came with few details, a day after the US struck three Iranian oil tankers in response to what it said was Iran launching ballistic missiles at US warships.
The new zone should be announced in the coming days and weeks and "will begin from the line of the US naval blockade, extend toward the Strait of Hormuz, and from this side continue into the Persian Gulf," Rezaei said.
"Any ship that enters this area with the intention of passing through the Strait of Hormuz and is identified will be placed on our sanctions list."
It is not clear where Iran defines the location of the weeks-long US blockade, which is aimed at Iranian ports and keeping Iran from shipping out its oil.
The US military has said more than 20 warships are supporting the blockade, which as of Sunday had redirected 92 commercial ships and disabled three.
The US has been introducing new measures to increase the economic pain on Iran after negotiations collapsed and no end to the intermittent fighting appears in sight.
Meanwhile, Iran continues to attack some ships trying to transit the strait, which has become an important source of leverage in the war that began February 28 with US and Israeli strikes.
Iran earlier on Sunday said it struck an unmanned US vessel trying to enter the Strait of Hormuz, a claim that the US military dismissed as a "total lie".
The strait is crucial to global oil and natural gas shipments and was seen as an international waterway before the war began.
On Sunday, US Energy Secretary Chris Wright said that on average, nine million barrels of oil a day are getting through the strait, which should help to relieve pressure on energy prices.
His estimate appeared to exceed average flows over the past 28 days through the strait, according to TankerTrackers.com and other sources.
Wright told CNN that with oil also flowing through pipelines in the region, "we're probably two-thirds or more of pre-conflict flows".
But those flows depend on the presence of the US navy to help escort tankers and provide some protection against possible Iranian attack.
Wright said he expected that other countries would eventually support the US navy's efforts.
Meanwhile, Rezaei in his interview with state TV insisted that "every day we are selling one million, one and a half million (barrels), as if Iran's oil production and trade are continuing as usual".
