The incident on Warraq island in Cairo came amid a government campaign to remove encroachments from state property and land, an interior ministry statement said.
A health ministry statement said one man was killed and 19 people were injured, and the interior ministry said 37 policemen and eviction workers were hurt in the clashes.
A large force that had headed to the island was met by "some of the encroachers who gathered to protest against the implementation of the removal orders," the interior ministry said.
The police arrested 10 people, the ministry said.
It said protesters fired birdshot and threw stones at officers, prompting police to use tear gas to disperse them.
The force was accompanying "a large number of senior officials from Giza province (part of Greater Cairo) and the ministries of agriculture, irrigation and religious endowments" which own land on Warraq, the interior ministry said.
It said Sunday's operation involved about 700 removal orders.
The delegation also planned to study legalising some current land ownership on the island.
Witnesses including a former head of the island's municipality told AFP they had not received advance warning about the move.
In May, President Abdel Fattah al-Sisi ordered a campaign to recover state-owned land which had been encroached upon.
The authorities announced in June that the government had retaken control of more than 919.4 thousand feddans, or around 386,150 hectares (95,390 acres).