This is a bit messier than I would normally like, but there weren't many options since the tabs are not input elements that can just be disabled.

Instead, I wrote a couple of scripts that clone all the nav elements into hidden contains and strips the default handlers off the originals.

A new handler is added to the elements, which validates the active page, and if the page is valid, it will trigger a click event on the hidden clone.

The page validation script leverages the parsley validation already built into Forms, so no extra checks/messages are needed.

$(document).ready(function(){
  // create container for cloned nav tabs
  let container = $('<div style="display:none !important;"></div>');
  
  // pagination tabs
  $('.cf-pagination-tabs li').each(function(){
    // clone tab to hidden container
    var c = $(this).clone(true, true);
    container.append(c);
    
    // remove/replace event handlers
    $(this).off().on('click',function(){
      // get results of page validation
      if (pageValid()) {
        $(c).click(); // trigger click on hidden tab
        if ($(this).is('li')) $(this).addClass('active'); // make tab active
      }
    });
  });
  $('.cf-pagination-tabs').parent().append(container);
  
  // navigation buttons
  $('.cf-pagination-btn').each(function(){
    // create container for nav buttons
    var box = $('<div style="display:none !important;"></div>');
    
    $(this).find('input').each(function(){
      // clone button to hidden container
      var c = $(this).clone(true,true);
      box.append(c);
      
      // remove/replace event handlers
      $(this).off().on('click',function(e){
        if (pageValid()) $(c).click(); // trigger click on hidden btn
      });
    });
    
    $(this).append(box);
  });
  
});

// page validation function
function pageValid(){
  var valid = true; // default output
  
  // validate fields on active page
  $('.cf-page.active :input:not([readonly]):visible').each(function(){
    // show validation errors
    $(this).parsley().validate();
    
    // change output for invalid field if none detected
    if (valid && !$(this).parsley().isValid()) {
      $(this).focus(); // focus on first error
      valid = false; // flag error
    }
  });

  return valid;
}

Everything seemed to work as expected on my end.