Those arrested have been identified as Babu (32), Om Prakash (24), Rahul (24), Ajay (25) and Kunal (20).
Three more persons have been identified and the police are looking out for them, DCP (south) Ishwar Singh said.
Kunal was earlier suspected to be a minor and his actual age was verified after scanning several documents, a senior official said.
The incidents came close on the heels of killing of a Congolese national that had triggered angry reaction by all the African countries. Their envoys had unitedly threatened to boycott the Africa Day celebrations of the Indian government last week, before they were persuaded against it.
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Police attributed two of Thursday's incidents to a dispute over African nationals playing loud music and other to a scuffle over public drinking.
A police official denied that rods or bats were used in the assaults, saying the nature of injuries would have been different then. He said a man had sustained an injury on his nose.
"Spoke to Commissioner of Police, Delhi regarding the incidents of physical assault against certain African nationals. Such incidents are condemnable," Singh tweeted.
"Instructed CP Delhi to take strict action against the attackers and increase patrolling in these areas to ensure security of everyone," he said in another tweet.
Prior to that, External Affairs Minister Sushma Swaraj tweeted that she had spoken to the Home Minister as well as Delhi Lt Governor Najeeb Jung over the incident, telling them to ensure security of African nationals. She said a sensitisation campaign will also be carried out in the areas where African nationals reside.
"I have asked Gen V K Singh, MoS and Secretary Amar Sinha to meet# African students who have announce(d) demonstration at Jantar Mantar," she added in another tweet.
Sinha, Secretary (Economic Relations) in the MEA has been in touch with African community following the attacks.
V K Singh, meanwhile, claimed that the attack on African nationals was a "minor scuffle" which the media was "blowing up" and questioned its motives.