China has so far invested $700 million and have provided jobs to 4,000 Sri Lankan citizens related to the project, he added.
"No matter how the international situation changes, China always facilitate great importance to Sino-Lanka relations and actively implements the consensus of the leaders of the two countries," Cheng said.
The project was completed 3 months ahead of its targeted 28 months.
The port city was a pet Chinese project under the regime of former president Mahinda Rajapaksa, the pro-China Sri Lankan leader between 2005 and 2015.
Chinese President Xi Jinping was the chief guest at the project's inauguration in 2014, just a few months ahead of Rajapaksa's ouster in the 2015 presidential election.
Rajapaksa's successor Maithripala Sirisena halted the project citing various irregularities, including the lack of environmental impact assessments.
The island nation's fisher community and environmental groups have called for the suspension of the project.
The Sirisena government's decision to suspend the project for several months drew fire from the Chinese government.
Once completed, it will be known as the Colombo International Financial City.
Invested and developed by the China Communications Construction Company Limited (CCCC), Colombo Port City is the largest project between China and Sri Lanka under the China-proposed Belt and Road Initiative, especially the 21st Century Maritime Silk Road.
China had claimed that the construction of the port city will also create job opportunities for the locals, with a total of 83,000 jobs expected in the 20 years from implementation to completion of the project.
The Silk Road Economic Belt and the 21st Century Maritime Silk Road, known as Belt and Road Initiative is President Xi's ambitious project.
Proposed in 2013, the multi-billion dollar project is aimed at building a trade and infrastructure network connecting Asia with Europe and Africa along the ancient trade routes.
Cash-rich China has invested millions of dollars in Sri Lanka's infrastructure since the end of a brutal civil war with the LTTE in 2009.
India has expressed concern on the Chinese port city in Colombo as it will be seen as an important hub on China's 'Belt and Road' concept.