The 30-year-old rap star has been in jail since July 5, after he was arrested in Stockholm, Sweden, prior to a music festival and charged with assault causing bodily harm.
Rocky is being detained pending a trial, which is due to start on July 30, but Trump has taken to Twitter to demand that he is freed immediately.
He tweeted: "Give A$AP Rocky his FREEDOM. We do so much for Sweden but it doesn't seem to work the other way around. Sweden should focus on its real crime problem! #FreeRocky.
"Very disappointed in Prime Minister Stefan Lofven for being unable to act. Sweden has let our African American Community down in the United States. I watched the tapes of A$AP Rocky, and he was being followed and harassed by troublemakers. Treat Americans fairly! #FreeRocky (sic)."
Trump previously revealed he had spoken to the Swedish Prime Minister on the phone about the case after Kanye West asked him to intervene.
He wrote on the micro-blogging platform: "Just had a very good call with @SwedishPM Stefan Lofven who assured me that American citizen A$AP Rocky will be treated fairly.
"Likewise, I assured him that A$AP was not a flight risk and offered to personally vouch for his bail, or an alternative.
"Our teams will be talking further, and we agreed to speak again in the next 48 hours! (sic)"
The office of the Swedish Prime Minister also offered an update on Rocky's situation.
A statement read: "It was a friendly and respectful phone call which lasted about 20 minutes.
"The Prime Minister made sure to point out ... the government neither can nor will try to influence the judicial process. (sic)"
Prior to his arrest, Rocky shared footage of the brawl on his Instagram account, which showed him attempting to break up the fight.
He accompanied the footage with the caption: "SO A FEW DRUG ADDICTS ARE NOT MY FANS , WE DONT KNOW THESE GUYS AND WE DIDNT WANT TROUBLE , THEY FOLLOWED US FOR 4 BLOCKS , AND THEY WERE SLAPPING GIRLS BUTTS WHO PASSED , GIVE ME A BREAK (sic)"
The video showed Rocky remaining relaxed throughout the row as he told one of the men to calm down, after he slapped his security guard over the head with headphones.
He said: "We don't want to fight y'all - we not trying to go to jail."
When the man asked for the headphones back, the rap star said: "I understand but you hit him with it."
He then said directly to the camera: "Just for the cameras, we don't want no problems with these boys, they keep following us." `
