Steel & Tube's said it had received a takeover offer form Fletcher Building at $1.70 a share, which it said "significantly undervalues" the company.
The cumulative value of the business is $282 million.
The company said the board had considered the non-binding indicative offer, received on 10 September, from Fletcher Building and had sought expert legal and commercial advice.
The board said proposed acquisition would need clearance under the Commerce Act, "which would take some time to work through due to Fletcher's vertical presence and significant size in several steel product markets".
Steel and Tube is involved in steel distribution, processing and fabrication. The company's shares last traded at $1.36.