He added: "The quake was felt very strongly, we expects more damage and more victims". The news and stories that matter, delivered weekday mornings.
The quakes led to the closure of the main airport in the province and cut off communication, officials said.
"There are reports that many buildings collapsed in the natural disaster", Sutopo said in a statement. "There is a ship washed ashore".
A powerful natural disaster rocked the Indonesian island of Sulawesi Friday - the latest in a series of recent quakes that killed almost 500 people on the in the country last month.
The tsunami up to 2 metres (six feet) high struck beaches as dusk fell in Palu, a sleepy but growing tourist resort, and the nearby fishing town of Donggala, closest to the epicenter of the quake 27 km away, officials said. It was followed by at least two dozen aftershocks.
Sulawesi is about 1600 kilometres north-east of Jakarta.
Amateur footage shown by local TV stations, which could not immediately be authenticated by Reuters, showed waters crashing into houses along Palu's shoreline, scattering shipping containers and flooding into a mosque in the city.
Photographs of many more dead bodies are also being circulated on social media.
"At this time, details and impacts of the 7.5 magnitude quake [reported as 7.7 locally] on Minahassa Peninsula, Sulawesi, and a subsequent tsunami are still emerging, and extent of the damage is unknown", the spokeswoman said. More than 600,000 people live in Donggala and Palu.
A spokeswoman for the Australian Department of Foreign Affairs said it was not aware of any Australians that have been affected by the natural disaster but was continuing to make inquiries with local authorities.
President Jokowi will arrive in Palu on Sunday to monitor the handling of the emergency.
Indonesian President Joko "Jokowi" Widodo tweeted late on Friday evening: "At sunset an quake hit Central Sulawesi and surroundings".
In August, more than 500 were killed in an quake that struck Indonesia's Lombok island.
Woman and children wailed hysterically in a video distributed by the National Disaster Mitigation Agency, which also released a photo showing a heavily damaged department store. Indonesia's deadliest ever tremor struck Sumatra island in 2014 and triggered a tsunami that killed almost 280,000 people in around a dozen countries along the Indian Ocean, with the biggest number of casualties registered in Indonesia.
Indonesia is prone to earthquakes because of its location on the "Ring of Fire", an arc of volcanoes and fault lines in the PacificBasin.