The day, which celebrates workers and the working classes, usually sees a major police deployment in Turkey every year.
Nearly 40 people, including journalists, trade unionists and opposition figures, were arrested in Istanbul on Tuesday ahead of International Workers' Day on 1 May, which has traditionally seen a police crackdown.
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The prosecutor general's office in the city told reporters that arrest and search warrants had been issued against 62 people, of whom 46 it deemed "likely to carry out attacks."
Of the 46, 39 were detained in Istanbul and in the nearby Kocaeli area, it added.
Turkey's MLSA, a press and legal freedom body, said police raids had been carried out at the home of a lawyer and the offices of opposition newspapers Özgür Gelecek and Yeni Demokrasi, where the doors were "kicked in."
According to a lawyer, Serhat Alan, whose home was searched, "custody documents concerning 46 people were presented to him," the MLSA said.
"Since this case is subject to a 24-hour confidentiality order, restrictions have been imposed on access to lawyers," it added.
The main pro-Kurdish Peoples' Equality and Democracy Party (DEM), which is the third-largest in the Turkish parliament, denounced what it said were "operations targeting the left and socialists" as well as student organisations before 1 May.
"Numerous comrades have been taken into custody," it said, adding that the actions were aimed at "shrinking the space for democratic politics" and that they would "deepen social tensions."
The annual day, which celebrates workers and the working classes, usually sees a major police deployment in Turkey every year, with a large area in the heart of Istanbul around Taksim Square sealed off on the previous evening.
Last year, protests moved to the Kadıköy area of the city and more than 400 people were arrested.