A twelve-week consultation is beginning on the issue and if implemented, the ban would make Wales the second area of the UK to end the physical punishment of children.
Scotland outlawed the physical punishment of children last year.
Alistair Thompson from the Be Reasonable campaign - a group supported by the Christian Institute, told Premier's News Hour the law is fine as it is.
He said: "There's been a lot of very emotive language used that changing law will stop assaulting children.
"Assaulting a child is already illegal. What is permissible at the moment is a gentle smack that can redden the skin temporarily but not leave any other mark."
In Wales, the government plans to remove the defence of reasonable punishment to the offences of battery and assault.
Mr Thompson told Premier parents are best placed to decide how to discipline their children.
He added: "It's important that the views of ordinary parents are communicated very clearly to the Welsh Government.
"We know from polling, we know from previous discussions that the vast majority of parents and families and indeed the general population oppose changing the law.
"The Be Reasonable campaign is saying to everybody who is listening... make sure you go online and take part in the consultation because otherwise this will be another sort of power grab by the state which will be dictating to parents how they can and cannot discipline their children and that's just not right."
Listen to Alistair Thompson from the Be Reasonable campaign speaking with Premier's Alex Williams:
