"There is no legal way to cancel the agreement, this would give a poor signal to international markets on the Greek government's credibility," Louka Katseli told Eleftherotypia daily.
"Cooperation with China is of strategic importance to Greece," said the minister, who also holds the shipping portfolio under the new socialist government that swept to power last month.
The new administration is in a tight spot over the 35-year concession of container facilities at the main Greek port of Piraeus to the Chinese trade giant, approved by the previous conservative government last year.
The socialists had criticised the deal as "colonial" whilst in opposition, but were cornered last month when Piraeus dockworkers began a series of rolling strikes that trapped thousands of containers in the harbour.
Their union wants the deal scrapped, fearing the new operators will bring large-scale layoffs and an influx of cheap Chinese goods will undermine the already shaky Greek family-owned store sector.
The latest strike began on November 3 and was to expire late Sunday, but the union announced another 48-hour stoppage for Monday and Tuesday.
The dockworkers say the government had failed to give assurances on labour relations and the extent of future state control over the facilities.
Katseli on Sunday ruled out the prospect of a civil mobilisation, despite calls for a firmer hand from the Greek commercial sector whose Christmas season orders have been thrown into disarray by the strike.
A lawsuit against the dockworkers by a commerce association in the Peloponnese region of Messinia is to be examined on Monday.
The minister has pledged to "exhaust" every legal option available under the agreement and European laws to improve the terms for the Greek state.
A socialist former minister of merchant marine, George Anomeritis, was last week appointed to head the Piraeus port authority and jumpstart the talks, amid reports that other ministers are questioning Katseli's handling of the crisis.
Under the deal, the concession of Piraeus' docks II and III to Cosco is to bring a guaranteed premium of 3.4 billion euros (five billion dollars) and boost the port's capacity by 250 percent.