Cook, 25, scored 25 goals in the National League last season, helping the Bluebirds to a mid-table finish.
He returned to Holker Street after a stint at Grimsby in July 2014.
"The lad wants to play League football and I can't and won't have a go at players who want to play at a higher level," Cox told BBC Radio Cumbria.
"There are clubs at our level who have come in for him, but his agent has categorically said he doesn't want to sign for another Conference club.
"It's one we might need to be patient on."

Using a pseudonym of His Royal Gingerness (HRG), the hacker told the BBC he wanted to highlight the website's "vulnerability".
It only took him a few minutes to hack into the site, he said.
Norwich International Airport director Richard Pace condemned the hacking as a crime that police were investigating.
HRG pointed out that while he made his attack to see if he could gain access, a more maliciously-minded intruder could have done damage.
He claimed he knew of someone who had planned to plant a bomb hoax in the system over Christmas, but said he was able to prevent that from happening.
While Mr Pace said the information website was not linked to the airport's operations system, he acknowledged that removing it was a serious inconvenience to passengers.
He admitted malicious hackers could have planted a bomb hoax on the site.
The airport's operations director promised a robust replacement site - with more secure protocols and systems - would be operational within weeks.
In the meantime, passengers can get information by calling 01603 411923.
HRG, who asked not to be identified because he fears prosecution, said he hacked the site "to see if I could".
"I found I could do it and then contacted the airport to let them know," he said.
"It took me between two to three minutes to do this. I do this mostly to see what vulnerability there are in modern systems."

About 2,000 pieces dating back more than 1,000 years were spotted on the seabed by members of a diving club, the Israeli Antiquities Authority said.
At first the group thought the coins were toys, but quickly realised the significance of their discovery.
The Antiquities Authority said the find was "so valuable that it's priceless".
Divers were exploring an ancient harbour in Caesarea when they came across the gold. They collected several coins and quickly returned to the shore to inform the director of the club.
Experts from the authority called to the site uncovered "almost 2,000 gold coins in different denominations" circulated by the Fatimid Caliphate, which ruled much of the Middle East and North Africa from 909 to 1171.
Kobi Sharvit, director of the marine archaeology unit at the Israel Antiquities Authority, said excavations would be carried out in the hope of shedding more light on the origin of the treasure.
He added: "There is probably a shipwreck there of an official treasury boat which was on its way to the central government in Egypt with taxes that had been collected.
"Perhaps the treasure of coins was meant to pay the salaries of the Fatimid military garrison which was stationed in Caesarea and protected the city."
He said another theory was that the treasure belonged to a large merchant ship that traded with the coastal cities and the port on the Mediterranean Sea.
The haul, which weighs 9kg (20lb), is believed to have been exposed as a result of winter storms.
It is now the property of the state and there was no finders' fee.
Barrow want to retain Andy Cook but expect the striker to explore opportunities in the Football League, says manager Paul Cox.
[NEXT_CONCEPT]
An airport has taken down its passenger information website after a hacker breached security systems, claiming they were too lax.
[NEXT_CONCEPT]
Scuba divers have inadvertently discovered the largest trove of gold coins ever found off Israel's Mediterranean coast.