The UN force in Côte d'Ivoire (Unoci) are "prepared for anything" after Laurent Gbagbo's order that they should leave by Monday, its spokesperson said Sunday.
UN Secretary General Ban Ki-moon has rejected Gbagbo's call and warned of "consequences" for anyone who attacks international troops.
"We're going to continue our patrols but we're not seeking confrontation. There are sensitive areas where we don't go, near the presidency," said Unoci's Hamadoun Touré.
"We're increasing our vigilance, and we're ready for anything."
The force is investigating Friday night's attack by uniformed men on a UN patrol, Touré said.
Unoci's operation officially ends on 20 December, which was set as the date to discuss renewing its mandate. The UN's mission ends on 31 December.
Ban said he was "deeply concerned" about that attack and two others, one by the Young Patriots movement which backs Gbagbo on Saturday.
"There will be consequences for those who have perpetrated or orchestrated any such actions or do so in the future," he warned.
About 800 UN troops are protecting the hotel where Gbagbo's rival, Alassane Ouattara, has his headquarters. The UN, along with Western and many African states, have recognised Ouattara as the winner of last month's presidential election.
Gbagbo also ordered France's 900 troops to leave. Paris said this week that its Licorne (Unicorn) contingent could be used to ensure the safe departure of the 15,000 French civilians living in Côte d'Ivoire if necessary.
The Unoci mission deployed in 2004 to help end a civil war between Gbagbo's southern forces and northern rebels dubbed the New Forces, who back Ouattara.
Gbagbo's order increase fears of a new conflict.
"Play time is over," Charles Blé Goudé, Gbagbo's minister for youth declared Sunday.
Blé Goudé, who has been subject to UN sanctions since 2006 for alleged beatings, rapes and extrajudicial killings" by militias he is accused of running.
"We are going to defend the sovereignty of our country until the last drop of our sweat. I urge all Ivorians to make themselves ready for this combat. We are going to totally liberate our country," he told the AFP news agency.
Responding to French President Nicolas Sarkozy's call on Gbagbo to stand down, Blé told a rally, "If Sarkozy plans military intervention, he'd better be ready to kill a lot of Ivorians."
A women's demonstration in Bassam, 40km north of Abidjan, was violently broken up, RFI's French service reports. They were trying to protest at the arrest by uniformed men of a number of Ouattara supporters which followed demonstrations in the town on Friday.