Some senior Conservatives have written to Tory MPs to raise concerns about the government's decision to give Huawei a role in the network.
The group, including four ex-cabinet ministers, want "high-risk" vendors ruled out now, or phased out over time.
But Mr Liu told the BBC's Andrew Marr Show "they were totally wrong".
"I think what they are doing is a kind of a witch-hunt," he said. "Huawei is a private-owned company, nothing to do with the Chinese government... the only problem they have is they are a Chinese company."
'Free market economy'
Several senior Conservatives have warned Huawei involvement in the UK's next generation mobile internet network poses a security risk and could lead to the first significant Commons rebellion against Boris Johnson's government.
But Mr Liu said the firm operated totally independently of the Chinese state and was a leader in the field of 5G.
"The reason why the [UK] prime minister decided to keep Huawei is he has a very ambitious plan for the UK, he wants to have 5G coverage in the UK by 2025, and Huawei can help."
But he criticised the 35% cap that the government had put on Huawei's involvement, saying it was not in keeping with the principle of a "free economy".
And, when asked about President Trump being unhappy with the UK, he said "I will leave the prime minister to deal with President Trump".
Mr Liu said: "The UK can only be great when it has own independent foreign policy. I hope the prime minister will stay with the decision because I think it's in interest of the UK and maintaining Britain's image as most open and free market economy in the world."
Foreign Secretary Dominic Raab has said the Huawei decision followed a "rigorous" review by security experts and that the firm's involvement would be restricted.
But the senior Conservatives have said there are alternatives to the Chinese firm.
The letter from Sir Iain Duncan Smith, Owen Paterson, David Davis, Damian Green, Tobias Ellwood and Bob Seely, which has been seen by the BBC, says some MPs were "working to find a better solution".
"We are seeking to identify a means by which we ensure that only trusted vendors are allowed as primary contractors into our critical national infrastructure," it says.
"Trusted vendors would be companies from countries that have fair market competition, rule of law, respect human rights, data privacy and non-coercive government agencies."
The signatories say they want the government to "rule out hi-tech from untrusted, high-risk vendors" in the UK's infrastructure, or to ensure future legislation includes "sunset clauses" to limit the length of time such companies can be used.
The letter comes after US vice-president Mike Pence said the US was "profoundly disappointed" with the UK's decision.
The UK government has said restrictions would be in place on Huawei's role in the 5G network.
These include: banning Huawei from supplying kit to "sensitive parts" of the network, only allowing it to account for 35% of the kit in a network's periphery, and excluding the firm's equipment from areas near military bases and nuclear sites.
But Sir Iain and the others behind the letter have also cited examples of other countries which they said had already rejected using Huawei in their 5G networks at all, including Australia, the US and Japan.