Justin Bieber -- Penis Is a Moving Target ... Hard to Blur

Miami Beach cops are having technical difficulties with Justin Bieber's penis ... because it moves too much.

Law enforcement sources tell us ... they fully intend to release more jailhouse videos of the dainty jailbird ... including one showing him peeing into the visible jail toilet. The judge previously ordered cops to blur Bieber's junk before releasing it ... we mean the video.

But there's a problem ... Our sources say they're having trouble obfuscating Bieber's genital area, because he moves as he pees. But they're also having technical issues blurring the video.

We're told the police tech team has been working on the problem non-stop since Tuesday.