Egypt's ruling military council says it will not tolerate any more strikes which disrupt the country's economy.
State television carried a statement in which the military said strikers would be "confronted".
Egypt's huge public sector has been hit by stoppages by groups including policemen and factory workers.
The army statement came at the end of a day in which millions of Egyptians had celebrated the victory of their revolution one week ago.
Cairo's Tahrir Square was again at the centre of events, with an estimated two million people gathering there to celebrate the removal of Hosni Mubarak and to pay tribute to the 365 people who died in the uprising.
The demonstration was also intended as a show of strength - a reminder to the current military rulers to keep their promise of a swift transition to democracy
By evening, the gathering had become a huge party, with music, singing, dancing, fireworks and food.
But the military statement struck a more sober tone.
The weeks of protests had already damaged the country's economy, with banks, offices and shops frequently closed, and the tourism sector badly affected.
Workers, inspired by the political protests, have also been staging strikes to demand better pay and conditions.
The military statement pointed to "some sectors that have... organised stoppages and protests, disrupting (economic) interests, halting the wheels of production and creating difficult economic conditions that could lead to the deterioration of the nation's economy."
"They will be confronted and legal steps will be taken against them to protect the security of the nation and citizens," the statement threatened.
I would just like to say i support the strikes in Egypt and the military now are sending out a worrying tone to their messages. Clamping down on strikes and campaigns for better working rights and conditions is not something that should be shut out without any further thought.
As you may or may not know i'm a pro union person belonging to one of the biggest trades unions in Britain today, Unite and i feel that union rightsand rightst o strike should always be protected.
There is still a element of protesters who still feel their demands have not been met by this military group in temporary charge in Egypt and i dont blame them for carrying on striking to get what they want. All this talk of them damaging the economy is a little like blackmail to get them to pipe down and accept what they have. Why should they ? they deserve better than what they have. The actions of workers in striking and taking over factories in Egypt has been simply inspirational that the workers have dared to fight back against the rulers there. I do hope they can hold out and be rewarded for their brave efforts there.
As at the end of the day waht workers gain now generationsof workers will benifit from in the long run. If you dont make a stand now you never will.