WBC champion Mayweather used the social networking site to entice a fight between two welterweight champions writing: "Step up Punk".
With boxing fans eager to see their pair battle, the unbeaten Mayweather was attempting to lure the Philippine into a Las Vegas bout to be staged on May 5.
And WBO champion Pacquiao insists he is keen to fight Mayweather.
"I want to fight him," Pacquiao said at a news conference with his promoter Bob Arum.
"This is the fight the world wants."
Despite both sides wanting the fight there are a number of complications particularly as Mayweather has only been given clearance to fight on May 5 in Las Vegas by a court.
The 34-year-old's 90-day prison sentence for domestic violence is due to start on June 1, while Mayweather is also demanding a set fee for the bout.
"Mayweather wants a guaranteed purse so what he has to do is get a promoter who can give him that guarantee," Pacquiao added.
"I don't have problems getting a guarantee because I have a promoter who will give me my guaranteed purse."
Arum added: "Mayweather has nobody on his side and Golden Boy Promotions is not going to guarantee his purse."
Mayweather had tweeted earlier this week: "Manny Pacquiao I'm calling you out let's fight May 5 and give the world what they want to see.
"My Jail Sentence [sic] was pushed back because the date was locked in. Step up Punk."
The pair had previously agreed to fight but the plans were derailed when both competitors accused each other of being scared to take on the challenge.
Arum, though, has insisted he will use back-up plans if there is no fight by the end of May with rematches against Juan Manuel Marquez or Miguel Cotto suggested.