The government has not set time limits for the operation, Malaysian Defense Minister Hishammuddin Hussein said in Australia on Wednesday.
He said he is 99.9% optimistic that the airliner will be spotted in the vast ocean.
The minister was present at the site when the search resumed in the ocean.
He thanked Australia and China for their participation in the operation.
A Malaysian vessel and a special sonar ProSAS are used in the search.
The Malaysia Airlines Boeing 777 disappeared on March 7 when it was on a flight from Kuala Lumpur to Beijing. Contact with the plane was lost about two hours after it took off. It was searched for in the ocean about 2,500 km west of Australia’s coast.