Even as Qihoo 360 is in the midst of a bitter feud with Chinese search engine leader Baidu, CEO Zhou Hongyi has promised not to enter the instant messaging market. The executive offered the guarantee while onstage with Tencent CEO Pony Ma at the China Internet Conference, as noted by TechWeb (translation).

He told Ma to “rest assured” that the company would never challenge’s Tencent’s IM dominance, which Ma reinforced on Tuesday with the revelation that his company’s WeChat messaging app has doubled its user base to 200 million. Zhou added that he could only watch from the sidelines as underdog startup Xiaomi competes against Tencent with its Miliao messaging service, which has about 17 million users.

Qihoo 360 was originally a vendor for anti-virus and security software before building its own version. The company also operates a browser, and has recently entered the search market. Tencent, for its part, rose to prominence with its QQ instant messaging service and has broadened into Web and social network-based gaming, micro-blogging and group messaging.

Frankly, given Tencent’s strength in the messaging space, Qihoo 360 isn’t make much of a sacrifice here, since it would have a steep uphill climb to gain users.

Qihoo 360’s promise not to compete against Tencent is, however, significant in light of the heated dispute that took place between the two companies in 2010. After Qihoo’s security software began blocking QQ, Tencent responded with its own blocks. As the disagreement escalated, the Chinese government got involved and ordered the two companies to make amends.

Since then, Qihoo has continued to build up a reputation for picking fights within the industry. For instance, Qihoo and Xiaomi butted heads earlier this year over smartphone pricing.

Image via Flickr / keso